An adaptive dynamic water level adjustable fish passage

Abstract

The present application belongs to the technical field of fish passage facility construction, and discloses a self-adaptive dynamic water level adjustable fish passage, which comprises a first fish passage arranged downstream of a dam and an adjustable fish passage arranged upstream of the dam and communicated with the dam; the adjustable fish passage comprises a plurality of piers and a fish pipe; the plurality of piers are vertically arranged at a preset interval upstream of the dam and used for supporting the fish pipe; one end of the fish pipe is communicated with the first fish passage, and the other end thereof is located upstream of the dam as a fish outlet; the fish pipe is transversely connected to the plurality of piers, and the fish pipe can slide along the elevation direction of the piers so as to adjust the position elevation of the fish outlet according to the dynamic water level. Through the height adjustment and the pier design, the fish pipe elevation can be flexibly and timely adjusted, and the water level with large amplitude can be adapted. The design reduces the cost, simplifies the operation, saves the reservoir space, promotes the sustainable development of water conservancy and hydropower projects, provides solid support for ecological protection, and embodies the dual values of engineering efficiency and environmental protection.

Description

TECHNICAL FIELD

[0001] The application discloses an adaptive dynamic water level adjustable fish passage, and belongs to the technical field of fish passage construction. BACKGROUND

[0002] Fishways serve as channels for fish migration and play a crucial role in maintaining the balance of aquatic ecosystems. However, with the continuous expansion of human activities, many fish's original migration channels have been destroyed, forcing people to take measures to protect this natural habit of fish. In water conservancy projects, in order to make up for this ecological gap, artificial water channels and other remedial measures are often built on water gates or dams to provide alternative channels for fish migration.

[0003] In view of the large changes in water level in the upstream reservoir area, traditional fixed fishways cannot meet the fish passage requirements of fish under different water level conditions. Therefore, new types of fishways such as floating adjustable fishways and gate fishways have emerged. These fishways adjust the overall or segmented lifting to adapt to the change of water level, ensuring the smooth migration of fish.

[0004] However, in practical applications, there are some problems to be solved in floating adjustable fishways. Due to the action of the existing floating device, the fishway may not meet the fish passage requirements in some sections during lifting, which will cause difficulties for fish to pass through. At the same time, the flow rate in the fishway may also be uneven, further affecting the migration effect of fish.

[0005] In addition, the floating or hydraulic device is usually arranged at the bottom of the water body. These devices are operated in a wet or underwater environment for a long time, facing challenges in layout, maintenance and repair management, etc. Due to the particularity of the environment, the performance of these devices may be affected, thereby reducing the stability and reliability of the fishway.

[0006] In addition, the length of the fishway is also greatly affected by the slope ratio and water level amplitude. Under the condition of a certain slope ratio, the larger the water level amplitude, the longer the required fishway length. This not only increases the difficulty and cost of the project, but also may have certain impact on the overall layout and ecological environment of the reservoir area.

[0007] Therefore, how to design a fishway that can adapt to large changes in water level, meet the migration needs of fish, and be easy to lay out and maintain is a technical problem to be solved in the current water conservancy field. SUMMARY

[0008] The purpose of the present application is to provide an adaptive dynamic water level adjustable fish passage to solve the technical problems that the traditional fixed fishway is difficult to adapt to the upstream water level change caused by dam construction, the traditional floating fishway is difficult to maintain the fishway slope ratio and straightness, and then affects the fish passage efficiency. In order to achieve the above purpose, the present application provides an adaptive dynamic water level adjustable fish passage, which comprises a first fish passage arranged downstream of a dam and an adjustable fish passage arranged upstream of the dam and communicated with the dam;

[0009] The adjustable fish passage comprises a plurality of piers and a fish pipe;

[0010] The plurality of piers are vertically arranged at a preset interval upstream of the dam, for providing support for the fish pipe;

[0011] One end of the fish pipe is communicated with the first fish passage, and the other end is located upstream of the dam as a fish outlet;

[0012] The fish pipe is transversely connected to the plurality of piers, and the fish pipe can slide along the pier elevation direction to adjust the position elevation of the fish outlet according to the dynamic water level.

[0013] Preferably, it further comprises a plurality of height adjusting devices;

[0014] The plurality of height adjusting devices are respectively arranged on the plurality of piers, for driving the fish pipe on the pier to slide to a preset elevation according to the dynamic water level.

[0015] Preferably, each height adjusting device comprises a driving mechanism and a transmission mechanism;

[0016] The driving mechanism is arranged at the top of the pier and connected with the transmission mechanism;

[0017] The transmission mechanism is connected with the fish pipe.

[0018] Preferably, it further comprises a support mechanism;

[0019] The support mechanism is connected with the transmission mechanism and bears the fish pipe, for driving the fish pipe to slide along the pier elevation direction.

[0020] Preferably, the support mechanism comprises a support rod and two groups of pulleys;

[0021] Each pier comprises an opposite group of slide rails;

[0022] The fish pipe is arranged on the support rod;

[0023] The two groups of pulleys are respectively arranged at both ends of the support rod and slide in the slide rails.

[0024] Preferably, the sensing device is further included;

[0025] The sensing device is arranged on the pier near the fish outlet, used for collecting real-time water level information of the upstream reservoir, and transmitting the real-time water level information to the driving mechanism.

[0026] Preferably, the fish pipe is provided with a trash rack at the fish outlet.

[0027] Preferably, the length of the fish pipe is determined according to the submerged elevation of the fish outlet and the water level amplitude upstream of the dam.

[0028] Preferably, the guide plate is further included;

[0029] The guide plate is arranged in the fish pipe along the extension direction of the fish pipe, used for optimizing the water flow turbulence.

[0030] Compared with the prior art, the adaptive dynamic water level adjustable fish passage of the present application has the following advantages: through the design of the height adjusting device and the pier, the adjustment flexibility and real-time performance of the fish pipe elevation are significantly improved. The fish passage of the present application is not only suitable for reservoirs with large amplitude changes in water level, but also suitable for reservoirs with small amplitude changes in water level. More importantly, the design greatly reduces the overall cost of the fish passage project, simplifies the operation process, and effectively saves valuable space resources in the reservoir area. This series of advantages not only promotes the sustainable development of water conservancy and hydropower projects, but also shows the value in improving the efficiency of the project. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The figure is a schematic diagram of the adjustable fish passage axis in the embodiment of the present application;

[0032] Figure 2 The figure is a schematic diagram of the cross section of the adjustable fish passage in the embodiment of the present application;

[0033] Figure 3 The figure is a schematic diagram of the connection between the fish pipe and the pier in the embodiment of the present application.

[0034] In the figure: 1, dam; 2, pier; 3, fish pipe; 31, fish outlet; 4, sensing device; 5, hoist house; 6, driving mechanism; 7, fulcrum; 71, support rod; 8, steel cable; 9, pulley; 10, guide plate; 11, steel ring. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0036] At present, in the prior art, multiple distributed fish outlets are usually arranged, and the operation sequence of the fish outlets is adjusted in real time according to the change of the reservoir water level, however, the operation is complex, and the cost is high. The slope ratio of the existing floating adjustable fishway does not meet the requirements, the flow rate is uneven, and the like. In addition, the existing gate type adjustable fishway has problems of water sensitivity of mechanical and electrical lifting devices, too high horizontal length requirement, inaccurate adjustment parameters, and the like.

[0037] Based on the above problems, the present application provides a self-adaptive dynamic water level adjustable fish passage, which can accurately adjust the posture of the fish passage according to the change of the reservoir water level, ensure that the fish passage is in a straight state in a slanting direction or a horizontal direction, make the flow rate in the fishway balanced and not disorderly, and improve the fish passing efficiency. The fish passage is located at the edge of the bank slope, and is convenient for maintenance and repair. The multi-pivot structure makes the fishway horizontally extendable, and the fishway can be extended to the end of the reservoir area, and can also adapt to large-amplitude water level changes. The specific embodiments of the present application will be described in detail below.

[0038] Please refer to Figure 1 As shown in the figure, the present application provides a self-adaptive dynamic water level adjustable fish passage, which comprises a first fish passage arranged downstream of a dam 1 and an adjustable fish passage arranged upstream of the dam 1 and communicated with the dam 1. The first fish passage is arranged downstream of the dam 1, and still uses a traditional fish passage or other fish passing facilities, which is not limited by the present application. The core of the present application is the adjustable fish passage arranged upstream of the dam 1 and communicated with the first fish passage. The adjustable fish passage comprises a plurality of piers 2 and a fish pipe 3. The plurality of piers 2 are vertically arranged at a preset interval upstream of the dam 1, and are used for supporting the fish pipe 3. One end of the fish pipe 3 is communicated with the first fish passage, and the other end is arranged as a fish outlet 31 upstream of the dam 1. The fish pipe 3 is transversely connected to the plurality of piers 2, and the fish pipe 3 can slide along the elevation direction of the piers 2, so as to adjust the position and elevation of the fish outlet 31 according to the dynamic water level.

[0039] Specifically, the adjustable fish passage includes a plurality of piers 2 and a fish pipe 3. The piers 2 are vertically arranged on the stable foundation upstream of the dam 1 at a predetermined interval and close to the edge of the bank. The main function of the piers 2 is to support the fish pipe 3 and ensure that the fish pipe 3 can remain stable under the impact of the water flow. In the embodiment, the connection between the fish pipe 3 and each pier 2 is denoted as a fulcrum 7. One end of the fish pipe 3 is closely connected to the first fish passage, ensuring that fish can swim smoothly from the downstream; and the other end is the fish outlet 31, which is located at a certain position upstream of the dam 1, facilitating the fish to swim out.

[0040] In a specific embodiment, as shown in Figure 2 The interval between the first pier 2 close to the dam 1 and the dam 1 and the distance between each adjacent pier 2 are both set to h1 meters, which aims to ensure the stability of the structure and the smoothness of the sliding of the fish pipe 3. The total number of piers 2 is m, which is determined according to the specific terrain and engineering requirements upstream of the dam 1. The fish outlet 31 of the fish pipe 3 is set at a height of 1.5 meters from the current water level, i.e., the submergence elevation of the fish outlet 31 is 1.5 meters. This setting aims to ensure that the water flow can be smoothly discharged, while the inside of the fish pipe 3 remains full, thereby effectively utilizing the power of the water flow to facilitate the fish to pass through the fish passage more smoothly. It should be understood that the submergence elevation of the fish outlet 31 is set by a person skilled in the art according to the experience value, which can be set according to the habits of fish, the speed of water flow, the amplitude of water level, etc. This is the common knowledge of a person skilled in the art, which will not be described here.

[0041] Further, a plurality of height adjustment devices are also included; the plurality of height adjustment devices are respectively arranged on the plurality of piers 2, and are used to drive the fish pipe 3 on the pier 2 according to the dynamic water level, so that the fish pipe 3 slides to a predetermined elevation.

[0042] In the present embodiment, a plurality of height adjustment devices are introduced, which are respectively arranged on the plurality of piers 2 and located in the hoist house 5 at the top of the pier 2. The core function of these devices is to accurately drive the fish pipe 3 on the pier 2 according to the change of the dynamic water level, so that the fish pipe 3 can slide to a predetermined elevation position, to ensure the smoothness and efficiency of the fish passage. The height adjustment devices are arranged on each of the plurality of piers 2, which can realize the synchronous adjustment of the fish pipe 3. When the water level changes, the multiple fulcrums 7 connecting the fish pipe 3 and the plurality of piers 2 will be adjusted at the same time in a coordinated manner, to ensure that the entire fish pipe 3 always maintains a straight line state. This straight line state is crucial to maintaining the stability of the flow state in the fish pipe 3, which can reduce the water flow resistance and improve the passing rate of fish, thereby further improving the fish passage efficiency.

[0043] Further, each height adjusting device comprises a driving mechanism 6 and a transmission mechanism; the driving mechanism 6 is arranged at the top of the pier 2 and connected with the transmission mechanism; the transmission mechanism is connected with the fish pipe 3.

[0044] Specifically, each height adjusting device is composed of a driving mechanism 6 and a transmission mechanism. The driving mechanism 6 is arranged at the top of the pier 2, specifically in the operating room 5, and is closely connected with the transmission mechanism, forming a compact and efficient working unit. The transmission mechanism is further connected with the fish pipe 3, and through its precise transmission, the power of the driving mechanism 6 is directly transmitted to the fish pipe 3, driving the fish pipe 3 to slide along the elevation direction of the pier 2.

[0045] Further, a supporting mechanism is also included; the supporting mechanism is connected with the transmission mechanism and bears the fish pipe 3, used to drive the fish pipe 3 to slide along the elevation direction of the pier 2.

[0046] In order to further enhance the stability and reliability of the sliding of the fish pipe 3, a supporting mechanism is designed. The supporting mechanism is closely connected with the transmission mechanism, used to bear the weight of the fish pipe 3, and under the driving of the transmission mechanism, drive the fish pipe 3 to slide smoothly and accurately along the elevation direction of the pier 2.

[0047] Further, the supporting mechanism specifically includes a supporting rod 71 and two groups of pulleys 9; each pier 2 includes an opposite group of slide rails; the fish pipe 3 is arranged on the supporting rod 71; the two groups of pulleys 9 are respectively arranged at both ends of the supporting rod 71 and slide in the slide rails.

[0048] Specifically, as shown in Figure 3 the supporting mechanism is composed of a supporting rod 71 and two groups of pulleys 9, forming a stable support system. The supporting rod 71 serves as a carrier for the fish pipe 3, used to bear the weight of the fish pipe 3 and the water flow inside. At the same time, each pier 2 is designed to have a vertical slot inside, with a set of opposite slide rails embedded in the vertical slot. The slide rails provide a precise sliding path for the pulleys 9. The pulleys 9 are respectively arranged at both ends of the supporting rod 71, embedded in the slide rails during use, and can slide smoothly along the slide rails. This design not only ensures the stability and accuracy of the fish pipe 3 during sliding, but also greatly reduces the frictional resistance during sliding, making the fish pipe 3 respond more smoothly to changes in water level. During the adjustment of the fish outlet of the fish pipe 3, the supporting rod 71 is particularly selected as a cylindrical shape to facilitate the forward and backward movement of the fish pipe 3 during adjustment. In addition, in a further embodiment, a steel ring 11 is added to the periphery of the fish pipe 3. The steel ring 11 maintains a certain pre-set gap with the fish pipe 3 and is fixed on the supporting rod 71. This design aims to provide the necessary space for the fish pipe 3 to move during dynamic changes, while effectively preventing the risk of movement caused by the drastic changes of the fish pipe 3.

[0049] In this embodiment, the winch or other device is used as the driving mechanism 6, and the steel cable 8 is used as the transmission mechanism. When it is necessary to adjust the position of the fish pipe 3, the winch will start and pull the steel cable 8, thereby driving the support rod 71 to move along the slide rail. During this process, the pulley 9 will roll in the slide rail, further reducing the frictional resistance, so that the fish pipe 3 can more easily reach the preset elevation position.

[0050] Further, the sensing device 4 is also included. The sensing device 4 is arranged on the pier 2 near the fish outlet 31, used to collect real-time water level information of the upstream reservoir, and transmit the real-time water level information to the driving mechanism 6.

[0051] Specifically, in order to realize real-time monitoring and accurate response to the change of the reservoir water level, the sensing device 4 is introduced. This device is arranged on the pier 2 near the fish outlet 31, and the position is selected to ensure that the real-time water level information of the upstream reservoir can be accurately captured. The sensing device 4 can collect the water level data of the reservoir in real time and convert it into an electrical signal for transmission. These real-time water level information is then transmitted to the driving mechanism 6 as an important basis for adjusting the position of the fish pipe 3. After receiving these information, the driving mechanism 6 will quickly calculate and analyze, and adjust the elevation position of the fish pipe 3 according to the need, to ensure that the fish outlet 31 always remains at the appropriate water level. It is worth noting that the sensing device 4 is arranged vertically in the elevation direction of the pier 2, which makes it more accurate to capture the subtle differences in water level changes. The sensing device 4 can be selected as a capacitive water level sensor, an ultrasonic water level sensor, or an optical water level sensor. The capacitive water level sensor is selected in this embodiment.

[0052] Further, the fish outlet 31 of the fish pipe 3 is provided with a trash rack.

[0053] Specifically, the main function of the trash rack is to block and intercept various pollutants floating upstream, such as branches, plastic bags, and waterweeds, to prevent them from entering the fish pipe 3 and causing unnecessary harm or hindrance to the fish. This design not only helps to keep the inside of the fish pipe 3 clean and unobstructed, but also improves the passing rate of the fish and ensures the efficient operation of the fish passage.

[0054] Further, the length of the fish pipe 3 is determined according to the submerged elevation of the fish outlet 31 and the water level amplitude upstream of the dam 1.

[0055] Specifically, in the construction process of the water conservancy and hydropower project, in order to ensure the smooth migration of fish, the upper reach end elevation of the first fish passage (traditional fishway) in the downstream area of the dam 1, the elevation of the adjustable fish passage in the upstream of the dam 1 in the horizontal state, and the difference between the dead water level elevation of the reservoir area and the submerged elevation of the fish pipe 3 in the adjustable fish passage are all located at the same elevation, so as to ensure that the water flow can smoothly connect each part. When designing the length of the fish pipe 3, the highest water level in the upstream of the dam 1 needs to be fully considered to ensure that the fish pipe 3 can cover the entire water level change range. With the increase of the water level amplitude in the upstream of the dam 1, the length of the fish pipe 3 also needs to be increased accordingly to ensure that fish can smoothly pass through at any water level.

[0056] The buttress 2 of the application is located at the edge of the bank slope, which is convenient for maintenance and repair. The buttresses 2 are extended in the horizontal direction, and the number of buttresses 2 increases the length of the fish pipe 3, so that the adjustable fish passage can adapt to large-amplitude water level changes.

[0057] When the water level in the upstream of the dam 1 rises, the position elevation of the fish outlet 31 of the fish pipe 3 becomes higher, and the angle between the fish pipe 3 and the horizontal plane is denoted as , The maximum value of the angle is related to the water level amplitude of the reservoir in the upstream of the dam 1, and is determined according to the maximum slope ratio that the fish can adapt to. It affects the elevation adjustment of the fish pipe 3 at different water levels and the passing efficiency of the fish. In order to ensure that the fish pipe 3 can be accurately adjusted according to the actual water level and keep the stability of the flow state in the fish pipe 3, the length of the fish pipe 3 is determined according to the determined submerged elevation of the fish outlet 31, the water level elevation and .

[0058] Specifically, in the embodiment, the length of the fish pipe 3 is equal to the product of the number of buttresses 2 and the spacing between the buttresses 2. That is, mh1; the highest elevation of the fish pipe 3 adjustment is denoted as: elevation max, and the lowest elevation, that is, the elevation of the fish pipe 3 in the horizontal direction, is denoted as: elevation min; the difference between the elevation max and the elevation min is related to the water level amplitude in the upstream of the dam 1.

[0059] Further, it also includes a baffle plate 10; the baffle plate 10 is arranged in the fish pipe 3 along the extension direction of the fish pipe 3, and is used for optimizing the turbulent flow of water. In order to further enhance the guiding property of the fish pipe 3, the baffle plate 10 is arranged in the fish pipe 3, and these plates can guide the fish to swim in the correct direction, thereby improving the passing efficiency of the fish.

[0060] The fish pipe 3 is an important channel connecting the traditional fishway and the reservoir, and various water-tight materials are used to make it, so as to ensure that it is firm and durable and can prevent water from leaking. The cross-sectional size meets the fish passing requirements, and the cross-sectional shape is circular or rectangular. Specifically, in the embodiment, the fish pipe 3 is made of underwater steel material, and the cross section is rectangular.

[0061] In this embodiment, the adjustable fish passage workflow is as follows:

[0062] First, in this embodiment, the submergence elevation of the fish pipe 3 is set to 1.5 meters. When the water level in the upstream reservoir area of ​​the dam changes, assuming that the water level at this time is elevation x, and this elevation is within the adjustable elevation range of the fish pipe 3, that is, elevation min < elevation x < elevation max, then the elevation of the fish outlet 31 at this time is the difference between elevation x and submergence elevation, that is, elevation x - 1.5 meters.

[0063] Next, we will use the tangent function from the trigonometric functions ( To calculate the elevation of each support point 7 (2nd pier), we can use the following formula based on geometric relationships:

[0064] at this time: ;

[0065] ;

[0066] ;

[0067] ; ...

[0069] ;

[0070] ;

[0071] In the formula, It is the angle between the fish tube and the horizontal plane. It is the spacing between each support pier. The number of supports, from the 1st to the 2nd. The abutments are distributed sequentially away from the dam.

[0072] Using the above calculation method, the elevation of the fish pipe 3 on each support pier 2 can be obtained at any water level in the reservoir. Then, the height adjustment device is used to drive the fish pipe 3 to slide and adjust on each support pier 2, so that the fish pipe 3 always remains at the preset elevation position. In this way, the elevation of the fish pipe 3 can be adjusted in real time according to the changes in the water level in the reservoir, ensuring the smooth and efficient passage of fish.

[0073] The adaptive dynamic water level adjustable fish passage channel of the present application significantly improves the flexibility and real-time of the fish pipe 3 elevation adjustment through the design of the height adjustment device and the pier 2. The fish passage channel of the present application is not only suitable for reservoirs with large amplitude changes in water level, but also suitable for reservoirs with small amplitude changes in water level. More importantly, the design greatly reduces the overall cost of the fish passage project, simplifies the operation process, and effectively saves valuable space resources in the reservoir area. A series of advantages not only promote the sustainable development of water conservancy and hydropower projects, but also show the value in improving engineering efficiency.

[0074] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. An adaptive dynamic water level adjustable fish passage, characterized in that, The adjustable fish passage comprises a plurality of piers and a fish pipe; The plurality of piers are vertically arranged at a preset interval upstream of the dam to provide support for the fish pipe; One end of the fish pipe is in communication with the first fish passage, and the other end is located upstream of the dam as a fish outlet; The fish pipe is transversely connected to the plurality of piers, and the fish pipe can slide in the pier elevation direction to adjust the position and elevation of the fish outlet according to the dynamic water level. Further comprising a plurality of height adjustment devices; 2. The self- adaptive dynamic water level adjustable fish passageway according to claim 1, wherein, The plurality of height adjustment devices are respectively arranged on the plurality of piers to drive the fish pipe on the pier according to the dynamic water level, so that the fish pipe slides to a preset elevation. Each of the height adjustment devices comprises a driving mechanism and a transmission mechanism; 3. The self- adaptive dynamic water level adjustable fish passageway according to claim 2, wherein, The driving mechanism is arranged on the top of the pier and connected to the transmission mechanism; The transmission mechanism is connected to the fish pipe. Further comprising a support mechanism; 4. The self- adaptive dynamic water level adjustable fish passageway according to claim 3, wherein, The support mechanism is connected to the transmission mechanism and carries the fish pipe to drive the fish pipe to slide in the pier elevation direction. The support mechanism specifically comprises a support rod and two sets of pulleys; 5. The self- adaptive dynamic water level adjustable fish passageway according to claim 4, wherein, Each pier comprises an opposite set of slide rails; The fish pipe is arranged on the support rod; The two sets of pulleys are respectively arranged at both ends of the support rod and slide in the slide rails. Further comprising a sensing device; 6. The self- adaptive dynamic water level adjustable fish passageway according to claim 3, wherein, The sensing device is arranged on the pier near the fish outlet to collect real-time water level information of the upstream reservoir and transmit the real-time water level information to the driving mechanism. The fish outlet of the fish pipe is provided with a trash rack.

7. The self- adaptive dynamic water level adjustable fish passageway according to claim 1, wherein, The length of the fish pipe is determined according to the submerged elevation of the fish outlet and the water level amplitude upstream of the dam.

8. The self- adaptive dynamic water level adjustable fish passageway according to claim 1, wherein, Further comprising a guide plate; 9. The adaptive, dynamic water level adjustable fish passageway of claim 1, wherein, The guide plate is arranged in the fish pipe along the extension direction of the fish pipe to optimize the water flow turbulence. ​

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