Experimental device and experimental method for interaction between internal solitary waves

Abstract

The invention discloses an experiment device and an experiment method for interaction between internal solitary waves, the device comprises a transparent water tank with a regular shape, a baffle group, a gate system and a water injection system, the baffle group is used for designing a flow channel of the internal solitary waves, and the baffle group is detachably assembled in the transparent water tank; the baffle plate group comprises at least two baffle plates, and all the baffle plates are jointly spliced into at least one flow channel which is mutually independent from the transparent water tank; when a plurality of flow channels exist, included angles required by experiments are formed among the flow channels; the water injection system comprises water injection equipment and embedded water injection ports distributed in the bottom surface of the transparent water tank; when the flow channels are constructed, a plurality of water injection ports are formed in each flow channel; all the water injection ports in the flow channel are connected to water injection equipment through communicating pipelines; the gate system comprises an openable gate matched with the runner; the gate is used for isolating the flow channel, and therefore wave making and wave absorbing are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of marine environment and internal wave simulation, and in particular relates to an experimental device and an experimental method for interaction between internal solitary waves. Background Art

[0002] As my country's development and utilization of marine resources continue to deepen, complex flow phenomena in the marine environment, especially internal solitary waves, have gradually become an important topic in research and engineering applications. Internal solitary waves are a special type of nonlinear wave whose waveform contains only one crest or trough and has highly concentrated energy, so they are also called solitons. The formation of internal solitary waves depends on the balance between dispersion effect and nonlinear effect, which enables them to maintain waveform stability during propagation and propagate over long distances. However, when internal solitary waves interact with each other during propagation, more complex flow phenomena will occur, which have a significant impact on the velocity, pressure and other characteristics of the flow field. Therefore, studying the interaction between internal solitary waves has important theoretical significance and engineering value for understanding their characteristics, designing marine structures and safe operations.

[0003] Internal solitary waves usually occur at the density jump layer inside the ocean, and have the characteristics of large scale, long propagation distance, and concentrated energy. There are two main formation mechanisms: First, when the tidal current passes through the seabed topography (such as seamounts, ridges or the edge of the continental shelf), the vertical movement of the fluid is restricted by the topography, the energy is concentrated and internal waves are excited, and the internal waves undergo nonlinear effects during the propagation process to form internal solitary waves; second, after the density jump layer is disturbed externally, internal solitary waves are excited under the action of gravity. The methods for studying the characteristics of internal solitary waves mainly include theoretical analysis, numerical simulation and model experiments. Among them, model experiments can accurately generate and measure the required internal solitary waves, and conduct systematic research by controlling the experimental environment. It is an indispensable technical means. Although some experimental flume design schemes have been proposed in the prior art, there is a lack of an experimental device that can be used to simulate the interaction between internal solitary waves. Summary of the invention

[0004] The purpose of the present invention is to provide an experimental device and an experimental method for interaction between internal solitary waves, so as to overcome the shortcomings of existing experimental water tanks, such as low modularity and inability to be used for wave-wave coupling process research, and better meet the experimental needs of studying the interaction process between internal solitary waves.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] An internal solitary wave interaction experimental device comprises a transparent water tank of regular shape, a baffle group, a gate system and a water injection system, wherein:

[0007] The baffle group is used to design the flow channel of the internal solitary wave, and the baffle group can be detachably assembled in the transparent water tank; the baffle group includes at least two baffles, and all the baffles are assembled together to form at least one flow channel independent of the transparent water tank; when there are multiple flow channels, the flow channels form an angle required by the experiment;

[0008] The water injection system includes a water injection device and an embedded water injection port distributed on the bottom surface of the transparent water tank; when constructing the flow channel, multiple water injection ports should be provided in each flow channel; all water injection ports in the flow channel are connected to the water injection device through a connecting pipe;

[0009] The gate system includes an openable and closable gate that cooperates with the flow channel; the gate is used to isolate the flow channel to achieve wave generation and wave elimination.

[0010] Furthermore, four baffles are used to construct two flow channels; wherein the ends of the baffles and the side walls of the transparent water tank, and the bottoms of the baffles and the bottom surface of the transparent water tank are sealed by glass glue or the like.

[0011] Furthermore, the water injection ports are distributed in an array on the bottom surface of the transparent water tank; the water injection ports include a circular water inlet cavity and a water injection pipe arranged at the bottom of the water inlet cavity, and a limiting clamp is distributed on the side wall of the water inlet cavity; a water retaining plate with an outer diameter smaller than the inner diameter of the water inlet cavity is arranged at the upper part of the water inlet cavity, and clamps are arranged around the water retaining plate, and the clamps are assembled in the limiting clamps, so that a plurality of arc-shaped water outlets are formed between the outer wall of the water retaining plate and the inner wall of the water inlet cavity.

[0012] Furthermore, when the water injection device is closed, all water injection ports inside the flow channel are connected through the connecting pipe to form a communicating vessel structure.

[0013] Furthermore, the gate system includes a bracket arranged outside the transparent water tank, a pulley block and a motor installed on the top of the bracket; the motor is connected to the gate through a flexible line assembled on the pulley block, and flexible sealing strips are installed on the sides and bottom of the gate;

[0014] When generating waves, the gate is placed in the designated position in the flow channel by the motor drive to close the gate, isolating the gravity collapse area in the flow channel inside the gate; when the motor drives the gate to be lifted to open the gate, the fluid in the gravity collapse area is released to the flow channel outside the gate to realize the wave generation process of internal solitary wave;

[0015] When wave breaking is performed, the gate is closed to isolate the inner solitary wave coming from a distance to the outside of the gate to achieve the wave breaking process.

[0016] An experimental method for non-zero angle interaction of internal solitary waves in two layers of fluid, based on the experimental device for interaction between internal solitary waves, comprises the following steps:

[0017] Step 10, determining the angle between the flow channels according to the experimental requirements, and constructing two flow channels inside the transparent water tank according to the angle through a baffle group, which are recorded as a first flow channel and a second flow channel;

[0018] Step 20, four gate systems are selected and arranged at both ends of the first flow channel and the second flow channel respectively; the gate systems arranged at the front end of the first flow channel and the front end of the second flow channel are used for wave generation, and a gravity collapse zone is formed between the gates in the gate system for wave generation and the nearest transparent water tank side wall, and the distance between the two is The gate system arranged at the rear end of the first flow channel and the rear end of the second flow channel is used for wave elimination. In the gate system for wave elimination, a wave elimination zone is formed between the gate and the nearest transparent water tank side wall, and the distance between the two is ; The area between the gravity collapse zone and the wave-breaking zone in the first flow channel and the second flow channel is the experimental section; represents the characteristic wavelength of the internal solitary wave to be constructed;

[0019] Step 30: close the gates at the front end of the first flow channel and the front end of the second flow channel, open the gates at the rear end of the first flow channel and the rear end of the second flow channel; and use a water injection device to inject water into the first flow channel and the second flow channel in sequence through the water injection port. The height of the upper fluid and Highly subsurface fluid;

[0020] Step 40, close the water injection device, add the upper fluid into the gravity collapse area of ​​the first flow channel and the second flow channel, and the lower fluid of the two gravity collapse areas will gradually flow into the experimental section and the wave-breaking area;

[0021] Step 50, record the length of the second flow channel as being greater than that of the first flow channel, and record the time for the internal solitary wave formed in the gravity collapse region of the second flow channel to propagate to the intersection of the first flow channel and the second flow channel as The time it takes to propagate to the wave-breaking zone of the second flow channel is recorded as The time it takes for the internal solitary wave formed in the gravity collapse zone of the first flow channel to propagate to the intersection of the first flow channel and the second flow channel is recorded as The time it takes to propagate to the wave-breaking zone of the first flow channel is recorded as ;but:

[0022] At time zero, the gate at the front end of the second flow channel is opened, so that an internal solitary wave is formed in the gravity collapse area of ​​the second flow channel and propagates along the second flow channel; The gate at the front end of the first flow channel is always opened, so that the gravity collapse area of ​​the first flow channel forms an internal solitary wave and propagates along the first flow channel;

[0023] Step 60, At time instant, the internal solitary waves in the first flow channel and the second flow channel interact with each other at the intersection of the first flow channel and the second flow channel;

[0024] Step 70, At time , the internal solitary wave in the first flow channel propagates to the wave-breaking zone. At this time, the gate at the rear end of the first flow channel is controlled to close, isolating the internal solitary wave to the wave-breaking zone. At time t, the internal solitary wave in the second flow channel propagates to the wave-breaking zone, and at this time, the gate at the rear end of the second flow channel is controlled to be closed.

[0025] Furthermore, the characteristic wavelength of the internal solitary wave Determined by the following formula:

[0026] ;

[0027] in, is the target amplitude of the inner solitary wave, and represents the thickness and density of the upper fluid injected into the gravity collapse zone, and Represents the thickness and density of the underlying fluid injected into the gravity collapse zone.

[0028] Furthermore, when the internal solitary wave to be constructed is a concave internal solitary wave, it is necessary to ensure that the density and thickness of the upper fluid are smaller than the density and thickness of the lower fluid.

[0029] Further, The calculation method is:

[0030] , ; is the velocity of the internal solitary wave, is the distance from the gravity collapse area of ​​the second flow channel to the intersection of the first flow channel and the second flow channel, is the acceleration due to gravity.

[0031] An experimental method for head-on collision of a single-mode solitary wave and a two-mode internal solitary wave, based on the experimental device for interaction between internal solitary waves, comprises the following steps:

[0032] Step 11, constructing a straight-line flow channel inside the transparent water tank through the baffle assembly and the side wall of the transparent water tank;

[0033] Step 21, a gate system is set at the front end and the rear end of the flow channel, so as to form a gravity collapse zone at the front end and the rear end of the flow channel, and the experimental section is between the two gravity collapse zones; the gravity collapse zone at the front end is used to form a single-mode internal solitary wave, and the gravity collapse zone at the rear end is used to form a second-mode internal solitary wave; the distance between the gate in the gate system at the front end and the front side wall of the transparent water tank is , the distance between the gate and the side wall of the water back channel in the gate system at the rear end is ; represents the characteristic wavelength of a solitary wave within a mode;

[0034] Step 31: close the gates at the front and rear ends of the flow channel, and use a water injection device to inject water into the flow channel through the water injection port. The height of the upper fluid and The middle fluid at the height; then part of the upper fluid is extracted from above the gravity collapse area at the rear end, and the middle fluid in the experimental section will flow to the gravity collapse area at the rear end;

[0035] Step 41, again use the water injection equipment to inject water into the flow channel through the water injection port The lower fluid of the height is then added with half of the upper fluid extracted from the gravity collapse zone at the rear end; the lower fluid in the gravity collapse zone at the rear end will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a two-mode internal solitary wave in the gravity collapse zone at the rear end;

[0036] Step 51, adding an upper layer of fluid into the gravity collapse zone at the front end from above; the lower layer of fluid in the gravity collapse zone at the front end will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a mode of internal solitary wave in the gravity collapse zone at the front end;

[0037] Step 61, record the time when the second mode internal solitary wave propagates to the middle of the experimental section as , the time it takes to propagate to the front gravity collapse zone is ; The time for a mode internal solitary wave to propagate to the middle of the experimental section is recorded as , the time it takes to propagate to the gravity collapse zone at the rear end is ;but:

[0038] At time zero, the gate at the rear end is first opened to form a two-mode internal solitary wave that propagates toward the front end of the flow channel; then The gate at the front end is always opened to form a single-mode internal solitary wave that propagates to the rear end of the flow channel; the single-mode internal solitary wave and the second-mode internal solitary wave interact with each other in the experimental section;

[0039] Step 71, manually move the gate at the rear end toward the front end, so that the distance between the gate and the rear side wall of the transparent water tank increases to ; then At time 1, the solitary wave in mode 1 first propagates to the gravity collapse zone at the rear end, at which time the gate at the rear end is closed; finally, at At time t, the solitary wave in the second mode propagates to the gravity collapse zone at the front end, and the experiment ends after the gate at the front end is closed.

[0040] Furthermore, the characteristic wavelength of a solitary wave within a mode is The calculation formula is:

[0041] ;

[0042] In the above formula, is the target amplitude of a solitary wave within a mode, and represents the thickness and density of the upper fluid injected into the experimental section, and represents the thickness and density of the middle fluid injected into the experimental section, and represents the thickness and density of the lower fluid injected in the experimental section; .

[0043] Compared with the prior art, the present invention has the following technical features:

[0044] 1. The baffle set in the present invention can be directly placed inside the transparent water tank and fixed by the pressure generated by the water flow and glass glue, etc., which is convenient for quick replacement and maintenance; users can flexibly configure or replace the baffles according to experimental requirements to form different types of flow channels, thereby significantly improving the flexibility and efficiency of the experiment.

[0045] 2. There are multiple embedded water inlets at the bottom of the transparent water tank, which can be quickly activated or deactivated; this design can ensure the existence of water inlets inside the flow channel under different flow channel settings, and the water injection process has little disturbance to the fluid in the tank.

[0046] 3. The gate system is placed on the ground, independent of the transparent water tank, and can be used on either side of the flow channel. The automatic opening and closing of the gate can achieve rapid conversion between wave generation and wave elimination.

[0047] 4. The device of the present invention has the advantages of simple operation, wide applicability, strong expandability, and easy module replacement; the device can not only generate typical internal solitary waves, but also can be used for experimental research on complex flow processes such as wave-body coupling and wave-wave coupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the overall structure of the experimental device of the present invention;

[0049] Figure 2 It is a schematic diagram of the water injection port structure in the water injection system;

[0050] Figure 3 It is a top view of a transparent water tank, and on the right side are four different types of flow channel structures;

[0051] Figure 4 It is a schematic diagram of the structure of the gate system;

[0052] Figure 5 Schematic diagram of the flow channel structure used in the experimental method of non-zero angle interaction of internal solitary waves in two-layer fluids;

[0053] Figure 6 (a) to (f) are schematic diagrams of the fluid changes in the flow channel at different stages in the experimental method of non-zero angle interaction of internal solitary waves in two layers of fluid;

[0054] Figure 7 It is the fluid interface before, during and after the internal solitary wave interaction in the experimental method of non-zero angle interaction of internal solitary waves in two layers of fluid;

[0055] Figure 8 (a) to (f) are schematic diagrams of different stages of the formation of gravity collapse zones at the front and rear ends of the flow channel in the head-on collision experimental method of a single-mode solitary wave and a second-mode internal solitary wave;

[0056] Fig. 9 (a) to (f) are schematic diagrams of different stages of the interaction between a single-mode internal solitary wave and a second-mode internal solitary wave in the head-on collision experimental method.

[0057] Explanation of reference numerals in the figure: 1 transparent water tank, 2 baffle group, 21 baffle, 3 gate system, 31 bracket, 32 pulley block, 33 flexible line, 34 gate, 35 motor, 4 water injection system, 41 water injection port, 42 water injection pipe, 43 water inlet cavity, 44 water retaining plate, 45 limit bayonet, 46 water outlet, 5 flow channel, 51 first flow channel, 52 second flow channel. DETAILED DESCRIPTION

[0058] The present invention first provides an internal solitary wave interaction experimental device, comprising a transparent water tank 1 of regular shape, a baffle group 2, a gate system 3 and a water injection system 4, wherein:

[0059] The baffle set 2 is used to design the flow channel 5 of the internal solitary wave, and the baffle set 2 can be detachably assembled in the transparent water tank 1; the baffle set 2 includes at least two baffles 21, and all the baffles 21 are assembled together to form at least one flow channel 5 independent of the transparent water tank 1; when there are multiple flow channels 5, the flow channels 5 form an angle required by the experiment;

[0060] The water injection system 4 includes a water injection device and an embedded water injection port 41 distributed on the bottom surface of the transparent water tank 1; when constructing the flow channel 5, a plurality of water injection ports 41 should be provided in each flow channel 5; all water injection ports 41 inside the flow channel 5 are connected to the water injection device through a connecting pipe;

[0061] The gate system 3 includes an openable and closable gate 34 that cooperates with the flow channel 5; the gate 34 is used to isolate the flow channel 5, thereby achieving wave generation and wave elimination.

[0062] The specific design of the experimental device of the present invention is further described below.

[0063] 1. Transparent sink 1.

[0064] See attached Figure 1 The transparent water tank 1 in the present invention is of regular shape, for example, a rectangular transparent water tank 1 or a circular transparent water tank 1. Figure 1 The example in FIG. 1 shows the structure of a rectangular transparent water tank 1. The transparent structure is used to facilitate observation of the interior of the flow channel 5 during the experiment.

[0065] 2. Baffle set 2.

[0066] The baffle set 2 is used to design the flow channel 5, which includes at least two baffles 21; Figure 3 , Figure 3 Several different forms of flow channels 5 are given on the right side; when two baffles 21 are used, a straight-line flow channel 5 can be constructed in combination with the side wall of the transparent water tank 1; and when four baffles 21 are used, two flow channels 5 with the angle required for the experiment can be formed through the combination of the baffles 21; the design of the angle is determined according to actual needs, so that the two flow channels 5 can be cross-shaped, fork-shaped, etc.

[0067] This scheme takes the construction of two forked flow channels 5 with a certain angle as an example, see Figure 3 Four baffles 21 are arranged in the transparent water tank 1, wherein the ends of the baffles 21 and the side walls of the transparent water tank 1, and the bottoms of the baffles 21 and the bottom surface of the transparent water tank 1 are sealed by glass glue or the like, so that the constructed flow channel 5 and the transparent water tank 1 are independent of each other and are not connected; by replacing baffles 21 of different shapes, the construction of different types of flow channels 5 can be achieved.

[0068] 3. Gate system3.

[0069] See also Figure 1 The gate system 3 in this scheme includes a bracket 31 arranged outside the transparent water tank 1, a pulley block 32 installed on the top of the bracket 31, and a motor 35; the motor 35 is connected to the gate 34 through a flexible line 33 assembled on the pulley block 32, and flexible sealing strips are installed on the sides and bottom of the gate 34.

[0070] Gate system 3 is used for wave breaking and wave creation:

[0071] When wave generation is performed, the gate 34 is driven by the motor 35 to be placed from top to bottom into the designated position in the flow channel 5 to close the gate 34, and the flexible sealing strip ensures the seal between the gate 34 and the bottom surface of the transparent water tank 1 in the flow channel 5, so that the gate 34 can be used to isolate a gravity collapse area (gravity potential well) in the flow channel 5 inside the gate 34; when the motor 35 drives the gate 34 to be lifted up to open the gate 34, the fluid in the gravity collapse area is released to the flow channel 5 outside the gate 34 to realize the wave generation process of the internal solitary wave.

[0072] When wave breaking is performed, the gate 34 can be closed to isolate the inner solitary wave coming from a distance to the outside of the gate 34 so that it does not pollute the inner area of ​​the gate 34, thereby achieving the wave breaking process.

[0073] The isolation position of the gate 34 in the flow channel 5 is adjusted by changing the position of the bracket 31 ; the number of gate systems 3 is set according to experimental requirements.

[0074] 4. Water injection system4.

[0075] The water injection system 4 is used to inject water into the flow channel 5 to meet the experimental requirements; in this solution, the water injection system 4 includes water injection equipment, water injection ports 41 and connecting pipes; the water injection equipment can be, for example, a water pump, and is connected to all water injection ports 41 located inside the flow channel 5 through connecting pipes.

[0076] like Figure 1 and Figure 3 As shown, in this solution, the water inlets 41 are distributed in an array on the bottom surface of the transparent water tank 1 and are designed to be embedded; Figure 2 As shown; the water injection port 41 includes a circular water inlet chamber 43 and a water injection pipe 42 arranged at the bottom of the water inlet chamber 43, and a limiting clamp 45 is distributed on the side wall of the water inlet chamber 43; a water retaining plate 44 with an outer diameter smaller than the inner diameter of the water inlet chamber 43 is arranged at the upper part of the water inlet chamber 43, and blocks are arranged around the water retaining plate 44, and the blocks are assembled in the limiting clamp 45, so that a plurality of arc-shaped water outlets 46 are formed between the outer wall of the water retaining plate 44 and the inner wall of the water inlet chamber 43.

[0077] The water injection device provides fluid to the water injection port 41 through a connecting pipeline. After the fluid enters the water inlet chamber 43 through the water injection pipe 42, it is blocked by the water retaining plate 44 to offset the upward impact force. At this time, the fluid will diffuse around the water retaining plate 44 and gradually overflow from the water outlet 46 to the inside of the flow channel 5.

[0078] When the water injection device is closed, all the water injection ports 41 inside the flow channel 5 are still connected through the connecting pipe to form a communicating vessel structure.

[0079] The water injection port 41 structure design adopted in the present solution can reduce the disturbance of the existing fluid in the flow channel 5 during the fluid injection process, thereby reducing the impact on the fluid.

[0080] It should be noted that, in order to ensure smooth water injection into the flow channel 5 , when constructing the flow channel 5 , a plurality of water injection ports 41 should be provided in each flow channel 5 .

[0081] On the basis of the above technical solution, the present invention provides an experimental method for non-zero angle interaction of internal solitary waves in two layers of fluid, comprising the following steps:

[0082] Step 10, determine the angle between the flow channels 5 according to the experimental requirements, and construct two flow channels 5 inside the transparent water tank 1 according to the angle through the baffle group 2, which are recorded as the first flow channel 51 and the second flow channel 52; wherein the first flow channel 51 is parallel to the side wall of the transparent water tank 1, see Figure 5 .

[0083] Step 20, four gate systems 3 are selected and arranged at both ends of the first flow channel 51 and the second flow channel 52 respectively; the gate systems 3 arranged at the front end of the first flow channel 51 and the front end of the second flow channel 52 are used for wave generation, and a gravity collapse zone is formed between the gate 34 in the gate system 3 used for wave generation and the nearest side wall of the transparent water tank 1, and the distance between the two (the gate 34 and the side wall of the transparent water tank 1) is The gate system 3 arranged at the rear end of the first flow channel 51 and the rear end of the second flow channel 52 is used for wave elimination. A wave elimination zone is formed between the gate 34 in the gate system 3 for wave elimination and the nearest side wall of the transparent water tank 1, and the distance between the gate 34 and the side wall of the transparent water tank 1 is ; The area between the gravity collapse zone and the wave-breaking zone in the first flow channel 51 and the second flow channel 52 is the experimental section.

[0084] in represents the characteristic wavelength of the internal solitary wave to be constructed, which is determined by the following formula:

[0085] ;

[0086] in, is the target amplitude of the inner solitary wave, and represents the thickness and density of the upper fluid injected into the gravity collapse zone, and represents the thickness and density of the lower fluid injected into the gravity collapse zone; when the internal solitary wave to be constructed is a concave internal solitary wave, it is necessary to ensure that the density and thickness of the upper fluid are smaller than the density and thickness of the lower fluid. In this embodiment, Take 0.05m, Take 1000kg / m 3 , Take 0.25m, Take 1020kg / m 3 .

[0087] The gravity collapse areas of the first flow channel 51 and the second flow channel 52 do not affect each other, so the generated internal solitary waves are independent of each other in the initial stage and only interact with each other at the intersection of the flow channels 5 .

[0088] Step 30: close the gate 34 at the front end of the first flow channel 51 and the front end of the second flow channel 52, open the gate 34 at the rear end of the first flow channel 51 and the rear end of the second flow channel 52; and use a water injection device to inject water into the first flow channel 51 and the second flow channel 52 in sequence through the water injection port 41. The height of the upper fluid and Height of lower fluid, see Figure 6 The light blue and dark blue areas in (a).

[0089] Step 40, close the water injection device, at this time, the water injection ports 41 in the first flow channel 51 and the second flow channel 52 are connected through the connecting pipe; add the upper layer fluid to the gravity collapse area of ​​the first flow channel 51 and the second flow channel 52, then due to the connection between the water injection ports 41, the lower layer fluid of the two gravity collapse areas will gradually flow into the experimental section and the wave-breaking area, such as Figure 6 as shown in (b).

[0090] In this step, the gravity collapse method is used to construct a fluid density layer different from that in other areas in the gravity collapse area and release it to form an internal solitary wave.

[0091] Step 50, record that the length of the second flow channel 52 is greater than that of the first flow channel 51, and the time for the internal solitary wave formed in the gravity collapse area of ​​the second flow channel 52 to propagate to the intersection of the first flow channel 51 and the second flow channel 52 is recorded as The time it takes to propagate to the wave-breaking zone of the second flow channel 52 is recorded as The time for the internal solitary wave formed in the gravity collapse zone of the first flow channel 51 to propagate to the intersection of the first flow channel 51 and the second flow channel 52 is recorded as The time it takes to propagate to the wave-breaking zone of the first flow channel 51 is recorded as ;but:

[0092] At time zero, the gate 34 at the front end of the second flow channel 52 is opened, so that the gravity collapse area of ​​the second flow channel 52 forms an internal solitary wave and propagates along the second flow channel 52; The gate 34 at the front end of the first flow channel 51 is always opened, so that the gravity collapse area of ​​the first flow channel 51 forms an internal solitary wave and propagates along the first flow channel 51. Figure 6 as shown in (c).

[0093] in, The calculation method is: , ; is the velocity of the internal solitary wave, is the distance from the gravity collapse area of ​​the second flow channel 52 to the intersection of the first flow channel 51 and the second flow channel 52, is the acceleration due to gravity.

[0094] the remaining , and The calculation method is the same, just replace In The corresponding distance can be used.

[0095] Step 60, At time , the internal solitary waves in the first flow channel 51 and the second flow channel 52 interact with each other at the intersection of the first flow channel 51 and the second flow channel 52, such as Figure 6 As shown in (d); in this experiment, both internal solitary waves are manifested as an increase in amplitude.

[0096] Step 70, after the internal solitary waves of the first flow channel 51 and the second flow channel 52 interact with each other, they will continue to propagate along the experimental sections of the first flow channel 51 and the second flow channel 52, such as Figure 6 As shown in (e); At time t, the internal solitary wave in the first flow channel 51 propagates to the wave-breaking zone. At this time, the gate 34 at the rear end of the first flow channel 51 is controlled to be closed to isolate the internal solitary wave to the wave-breaking zone to prevent it from propagating back and contaminating the experimental section. Figure 6 As shown in (f); similarly, At time t, the internal solitary wave in the second flow channel 52 propagates to the wave-breaking zone, and at this time, the gate 34 at the rear end of the second flow channel 52 is controlled to be closed.

[0097] In the above experiment, the internal solitary wave generation and elimination methods of the first flow channel 51 and the second flow channel 52 are consistent, but due to the difference in wave amplitude and wave velocity, the gravity collapse zone parameters and the movement time of the gate 34 are slightly different. The above experiment can be combined with fluid dyeing, PIV and other methods to observe the flow field, and structures can be placed at the intersection of the first flow channel 51 and the second flow channel 52 to further study the internal solitary wave effect.

[0098] On the basis of the above technical solution, the present invention also provides an experimental method for the head-on collision of a solitary wave of a mode and a solitary wave of a mode in a three-layer fluid. The method needs to construct three layers of fluid, namely, upper, middle and lower layers, and only needs one flow channel 5. The specific steps are as follows:

[0099] Step 11, construct a straight-line flow channel 5 inside the transparent water tank 1 through the baffle set 2 and the side wall of the transparent water tank 1, such as Figure 3 as shown on the right.

[0100] Step 21, a gate system 3 is provided at the front end and the rear end of the flow channel 5, so that a gravity collapse zone is formed at the front end and the rear end of the flow channel 5, and the experimental section is between the two gravity collapse zones; the gravity collapse zone at the front end is used to form a single-mode internal solitary wave, and the gravity collapse zone at the rear end is used to form a second-mode internal solitary wave; the distance between the gate 34 in the gate system 3 at the front end and the front side wall of the transparent water tank 1 is , the distance between the gate 34 in the gate system 3 at the rear end and the side wall of the water back tank is , which is because the width of the gravity collapse zone required for the two-mode internal solitary wave is narrow when the density distribution is consistent.

[0101] in, It represents the characteristic wavelength of a solitary wave in a mode, and the calculation formula is as follows:

[0102] ;

[0103] In the above formula, is the target amplitude of a solitary wave within a mode, and represents the thickness and density of the upper fluid injected into the experimental section, and represents the thickness and density of the middle fluid injected into the experimental section, and represents the thickness and density of the lower fluid injected into the experimental section; in general, .

[0104] In this embodiment, Take 0.05m, Take 1000kg / m 3 ; Take 0.05m, Take 1010kg / m 3 ; Take 0.25m, Take 1020kg / m 3 .

[0105] Step 31, close the gates 34 at the front and rear ends of the flow channel 5, and use a water injection device to inject water into the flow channel 5 through the water injection port 41 in sequence. The height of the upper fluid and High intermediate fluid, see Figure 8 (a) and (b) are shown; then part of the upper fluid is extracted from the gravity collapse area at the rear end. According to the principle of communicating vessels, the middle fluid in the experimental section will flow to the gravity collapse area at the rear end, as shown in Figure 8 as shown in (c).

[0106] Step 41, again use the water injection equipment to inject water into the flow channel 5 through the water injection port 41 The height of the lower fluid, such as Figure 8 As shown in (d); then about half of the upper fluid extracted is added from the upper part of the gravity collapse zone at the rear end; in this process, the lower fluid in the gravity collapse zone at the rear end will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a two-mode internal solitary wave in the gravity collapse zone at the rear end, as shown in Figure 8 As shown in (e).

[0107] Step 51, adding the upper layer fluid from the front gravity collapse area to the front gravity collapse area; in this process, the lower layer fluid in the front gravity collapse area will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a mode of internal solitary wave in the front gravity collapse area, such as Figure 8 As shown in (f).

[0108] Step 61, record the time when the second mode internal solitary wave propagates to the middle of the experimental section as , the time it takes to propagate to the front gravity collapse zone is ; The time for a mode internal solitary wave to propagate to the middle of the experimental section is recorded as , the time it takes to propagate to the gravity collapse zone at the rear end is ;in , , and It can be calculated by the distance and the wave velocity of the solitary wave in the first mode and the wave velocity of the solitary wave in the second mode; then:

[0109] Since the wave velocity of the second-mode internal solitary wave is much smaller than that of the first-mode internal solitary wave, the gate 34 at the rear end is opened first at time zero to form a second-mode internal solitary wave that propagates toward the front end of the flow channel 5, as shown in FIG. Fig. 9 as shown in (a); then The gate 34 at the front end is always opened to form a mode internal solitary wave that propagates toward the rear end of the flow channel 5, such as Fig. 9 (b) shows that the first mode internal solitary wave and the second mode internal solitary wave interact with each other in the experimental section, which is reflected in the increase of the lower wave surface amplitude and the decrease of the upper wave surface amplitude in this experiment, as shown in Fig. 9 As shown in (c) and (d).

[0110] Step 71, manually move the gate 34 at the rear end toward the front end, so that the distance between the gate 34 and the rear side wall of the transparent water tank 1 increases to ; then At time 1, a mode internal solitary wave first propagates to the gravity collapse zone at the rear end. At this time, the gate 34 at the rear end is closed to prevent the reflection of a mode internal solitary wave from contaminating the experimental section. Fig. 9 As shown in (e); finally At time 2, the solitary wave in the second mode propagates to the gravity collapse area at the front end, and the experiment ends after the gate 34 at the front end is closed. Fig. 9 As shown in (f).

[0111] The above experiment can be combined with fluid dyeing, PIV and other methods to observe the flow field, and structures can be placed in the experimental section of the flow channel 5 for further research.

[0112] In the above two experiments, the concave and convex single-mode internal solitary waves, the two-mode internal solitary waves, and the propagation direction of the internal solitary waves can be adjusted according to the experimental requirements; the experimental section can also be equipped with terrain models, structures, submersibles and other equipment to meet different experimental requirements. This device is mainly used for the generation and elimination of internal solitary waves, and there are no restrictions on the observation and post-processing operations of experimental phenomena. In addition, this device can be combined with particle image velocimetry (PIV), multi-view positioning, three-force balance and other equipment or technologies to further expand the scope of research.

[0113] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An experimental device for interaction between internal solitary waves, characterized in that: The invention comprises a transparent water tank (1) of regular shape, a baffle set (2), a gate system (3) and a water injection system (4), wherein: The baffle group (2) is used to design a flow channel (5) of an internal solitary wave, and the baffle group (2) is detachably assembled in a transparent water tank (1); the baffle group (2) includes at least two baffles (21), and all the baffles (21) are assembled together to form at least one flow channel (5) that is independent of the transparent water tank (1); when there are multiple flow channels (5), angles required for the experiment are formed between the flow channels (5); The water injection system (4) comprises a water injection device and embedded water injection ports (41) distributed on the bottom surface of the transparent water tank (1); when constructing the flow channel (5), a plurality of water injection ports (41) should be provided in each flow channel (5); all water injection ports (41) inside the flow channel (5) are connected to the water injection device via a connecting pipe; The gate system (3) comprises an openable and closable gate (34) cooperating with the flow channel (5); the gate (34) is used to isolate the flow channel (5), thereby achieving wave generation and wave elimination.

2. The internal solitary wave interaction experimental device according to claim 1, characterized in that: The water injection ports (41) are distributed in an array on the bottom surface of the transparent water tank (1); the water injection ports (41) include a circular water inlet cavity (43) and a water injection pipe (42) arranged at the bottom of the water inlet cavity (43); a limiting clamping opening (45) is distributed on the side wall of the water inlet cavity (43); a water retaining plate (44) having an outer diameter smaller than an inner diameter of the water inlet cavity (43) is arranged at the upper part of the water inlet cavity (43); clamping blocks are arranged around the water retaining plate (44), and the clamping blocks are assembled in the limiting clamping opening (45), so that a plurality of arc-shaped water outlets (46) are formed between the outer wall of the water retaining plate (44) and the inner wall of the water inlet cavity (43).

3. The internal solitary wave interaction experimental device according to claim 1, characterized in that: When the water injection device is closed, all water injection ports (41) inside the flow channel (5) are connected via the connecting pipeline to form a communicating vessel structure.

4. The internal solitary wave interaction experimental device according to claim 1, characterized in that: The gate system (3) comprises a bracket (31) arranged outside the transparent water tank (1), a pulley block (32) installed on the top of the bracket (31), and a motor (35); the motor (35) is connected to the gate (34) through a flexible line (33) mounted on the pulley block (32), and the side and bottom of the gate (34) are equipped with flexible sealing strips; When generating waves, the gate (34) is placed in a designated position in the flow channel (5) by driving the motor (35) to close the gate (34), thereby isolating a gravity collapse zone in the flow channel (5) inside the gate (34); when the motor (35) drives the gate (34) upward to open the gate (34), the fluid in the gravity collapse zone is released to the flow channel (5) outside the gate (34), thereby realizing the wave generation process of the internal solitary wave; When wave absorbing is performed, the gate (34) is closed to isolate the inner solitary wave coming from a distance to the outside of the gate (34), thereby achieving the wave absorbing process.

5. An experimental method for non-zero angle interaction of internal solitary waves in two layers of fluid, characterized in that: The method is based on the internal solitary wave interaction experimental device described in any one of claims 1 to 4, and comprises the following steps: Step 10, determining the angle between the flow channels (5) according to experimental requirements, and constructing two flow channels (5) at the angle inside the transparent water tank (1) through the baffle group (2), which are recorded as the first flow channel (51) and the second flow channel (52); Step 20, four gate systems (3) are selected and arranged at both ends of the first flow channel (51) and the second flow channel (52), respectively; wherein the gate systems (3) arranged at the front end of the first flow channel (51) and the front end of the second flow channel (52) are used for wave generation, and a gravity collapse zone is formed between the gate (34) in the gate system (3) used for wave generation and the side wall of the transparent water tank (1) closest to the gate system (3), and the distance between the two is The gate system (3) arranged at the rear end of the first flow channel (51) and the rear end of the second flow channel (52) is used for wave elimination, and a wave elimination zone is formed between the gate (34) in the gate system (3) for wave elimination and the side wall of the transparent water tank (1) closest to the gate system (3), and the distance between the two is ; The area between the gravity collapse zone and the wave-breaking zone in the first flow channel (51) and the second flow channel (52) is the experimental section; wherein represents the characteristic wavelength of the internal solitary wave to be constructed; Step 30, closing the gates (34) at the front end of the first flow channel (51) and the front end of the second flow channel (52), opening the gates (34) at the rear end of the first flow channel (51) and the rear end of the second flow channel (52); using a water injection device to inject water into the first flow channel (51) and the second flow channel (52) in sequence through the water injection port (41); The height of the upper fluid and Highly subsurface fluid; Step 40, closing the water injection device, adding the upper layer fluid into the gravity collapse area of ​​the first flow channel (51) and the second flow channel (52), and the lower layer fluid of the two gravity collapse areas will gradually flow into the experimental section and the wave-breaking area; Step 50, record that the length of the second flow channel (52) is greater than that of the first flow channel (51), and the time for the internal solitary wave formed in the gravity collapse zone of the second flow channel (52) to propagate to the intersection of the first flow channel (51) and the second flow channel (52) is recorded as The time it takes to propagate to the wave-breaking zone of the second flow channel (52) is recorded as The time for the internal solitary wave formed in the gravity collapse zone of the first flow channel (51) to propagate to the intersection of the first flow channel (51) and the second flow channel (52) is recorded as The time it takes to propagate to the wave-breaking zone of the first flow channel (51) is recorded as ;but: At time zero, the gate (34) at the front end of the second flow channel (52) is opened, so that the gravity collapse area of ​​the second flow channel (52) forms an internal solitary wave and propagates along the second flow channel (52); The gate (34) at the front end of the first flow channel (51) is constantly opened, so that an internal solitary wave is formed in the gravity collapse area of ​​the first flow channel (51) and propagates along the first flow channel (51); Step 60, At time t, the internal solitary waves in the first flow channel (51) and the second flow channel (52) interact with each other at the intersection of the first flow channel (51) and the second flow channel (52); Step 70, At time , the internal solitary wave in the first flow channel (51) propagates to the wave-breaking zone, and at this time, the gate (34) at the rear end of the first flow channel (51) is controlled to close, isolating the internal solitary wave to the wave-breaking zone; At time t, the internal solitary wave in the second flow channel (52) propagates to the wave-breaking zone, and at this time, the gate (34) at the rear end of the second flow channel (52) is controlled to close.

6. The experimental method for non-zero angle interaction of internal solitary waves in two-layer fluids according to claim 5, characterized in that: Characteristic wavelength of internal solitary waves Determined by the following formula: ； in, is the target amplitude of the inner solitary wave, and represents the thickness and density of the upper fluid injected into the gravity collapse zone, and Represents the thickness and density of the underlying fluid injected into the gravity collapse zone.

7. The experimental method for non-zero angle interaction of internal solitary waves in two-layer fluids according to claim 5, characterized in that: When the internal solitary wave to be constructed is a concave internal solitary wave, it is necessary to ensure that the density and thickness of the upper fluid are smaller than the density and thickness of the lower fluid.

8. The experimental method for non-zero angle interaction of internal solitary waves in two-layer fluids according to claim 6, characterized in that: The calculation method is: , ; is the velocity of the internal solitary wave, is the distance from the gravity collapse area of ​​the second flow channel (52) to the intersection of the first flow channel (51) and the second flow channel (52), is the acceleration due to gravity.

9. An experimental method for head-on collision of a single-mode solitary wave and a second-mode internal solitary wave, characterized in that: The method is based on the internal solitary wave interaction experimental device described in any one of claims 1 to 4, and comprises the following steps: Step 11, constructing a straight-line flow channel (5) inside the transparent water tank (1) through the baffle plate group (2) and the side wall of the transparent water tank (1); Step 21, a gate system (3) is provided at the front end and the rear end of the flow channel (5), so that a gravity collapse zone is formed at the front end and the rear end of the flow channel (5), and the experimental section is between the two gravity collapse zones; the gravity collapse zone at the front end is used to form a single-mode internal solitary wave, and the gravity collapse zone at the rear end is used to form a second-mode internal solitary wave; the distance between the gate (34) in the gate system (3) at the front end and the front side wall of the transparent water tank (1) is The distance between the gate (34) in the gate system (3) at the rear end and the side wall of the water back tank is ; represents the characteristic wavelength of a solitary wave within a mode; Step 31, close the gates (34) at the front and rear ends of the flow channel (5), and use a water injection device to inject water into the flow channel (5) through the water injection port (41) in sequence. The height of the upper fluid and The middle fluid at the height; then part of the upper fluid is extracted from above the gravity collapse area at the rear end, and the middle fluid in the experimental section will flow to the gravity collapse area at the rear end; Step 41, again use the water injection device to inject water into the flow channel (5) through the water injection port (41). The lower fluid of the height is then added with half of the upper fluid extracted from the gravity collapse zone at the rear end; the lower fluid in the gravity collapse zone at the rear end will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a two-mode internal solitary wave in the gravity collapse zone at the rear end; Step 51, adding an upper layer of fluid into the gravity collapse zone at the front end from above; the lower layer of fluid in the gravity collapse zone at the front end will partially flow into the experimental section, thereby forming a gravity potential well required for constructing a mode internal solitary wave in the gravity collapse zone at the front end; Step 61, record the time when the second mode internal solitary wave propagates to the middle of the experimental section as , the time it takes to propagate to the front gravity collapse zone is ; The time for a mode internal solitary wave to propagate to the middle of the experimental section is recorded as , the time it takes to propagate to the gravity collapse zone at the rear end is ;but: At time zero, the gate (34) at the rear end is first opened to form a two-mode internal solitary wave that propagates toward the front end of the flow channel (5); then The gate (34) at the front end is always opened to form a single-mode internal solitary wave that propagates toward the rear end of the flow channel (5); the single-mode internal solitary wave and the second-mode internal solitary wave interact with each other in the experimental section; Step 71, manually move the gate (34) at the rear end toward the front end, so that the distance between the gate (34) and the rear side wall of the transparent water tank (1) increases to ; then At time 1, the solitary wave in mode 1 first propagates to the gravity collapse zone at the rear end, at which time the gate (34) at the rear end is closed; finally, at At time t, the solitary wave in the second mode propagates to the gravity collapse zone at the front end, and the experiment ends after the gate (34) at the front end is closed.

10. The head-on collision experimental method of a single-mode solitary wave and a second-mode internal solitary wave according to claim 9, characterized in that: Characteristic wavelength of a solitary wave in one mode The calculation formula is: ； In the above formula, is the target amplitude of a solitary wave within a mode, and represents the thickness and density of the upper fluid injected into the experimental section, and represents the thickness and density of the middle fluid injected into the experimental section, and represents the thickness and density of the lower fluid injected in the experimental section; .

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