A method, device, medium, and product for generating turbulent flow based on pulsating velocity renormalization

Abstract

This invention discloses a method, device, medium, and product for generating turbulent inflow based on fluctuating velocity renormalization, relating to the field of computational fluid dynamics. This invention generates random fluctuating velocities at the inflow plane and continuously renormalizes these velocities over a downstream distance, ensuring that the turbulent kinetic energy distribution within this distance remains consistent with a given value. This establishes a coherent turbulent fluctuating structure within this distance that matches the given turbulent kinetic energy distribution.

Description

Technical Field

[0001] This invention relates to the field of computational fluid dynamics, specifically to a method, device, medium, and product for generating turbulent inflow based on pulsating velocity renormalization. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and may not constitute prior art.

[0003] The simulation capabilities of computational fluid dynamics have developed rapidly over the past few decades, and the Large Eddy Simulation (LES) method, with its high-fidelity simulation of turbulence, has gradually become a common method in aerospace vehicle design. However, for turbulent boundary layers evolving in space, the computational cost of LES remains enormous, with most of it used to simulate laminar boundary layer instability, transition, and the establishment of turbulent boundary layers. When the problem under study is concentrated in the turbulent region, if the influence of the upstream region on the turbulent region can be obtained through modeling, the simulation of the flow evolution in the upstream region can be eliminated. Turbulent fluctuation generation is one such modeling method.

[0004] The core idea of ​​Large Eddy Simulation (LES) is to directly solve the resolvable scale flow (large eddies) above the grid scale using governing equations, while subgrid-scale flow (small eddies) is simulated using models. A successful LES simulation requires capturing the self-organized coherent structure formed by the evolution of turbulent dynamics. This necessitates that the upstream turbulence generation method produce the most realistic self-organized coherent structure possible. Such coherent structures have a longer lifespan and are therefore the most representative of the upstream region's influence on the turbulent region.

[0005] Popular methods for generating turbulent fluctuations include random fluctuation methods, synthetic vortex methods, and cyclic-recalibration methods. Random fluctuation methods generate fluctuation information that dissipates rapidly downstream due to a lack of spatial and temporal correlation. Cyclic-recalibration methods extract fluctuation information already developed in the turbulent region, modify it based on boundary layer similarity, and add it as new turbulent fluctuations to the upstream region; however, this method is only suitable for problems with explicit boundary layer similarity. Synthetic vortex methods arrange vortices at the inlet of the turbulent region and use the vortex-induced velocity to characterize the turbulent fluctuation velocity. Because the vortex structure has some similarity to the coherent turbulent structure, the induced velocity is close to the actual turbulent fluctuation velocity, but its practical effect in flat plate boundary layer flows is not as good as the cyclic-recalibration method. Summary of the Invention

[0006] The purpose of this invention is to address the problems of lack of coherent structure, computational complexity, and limited applicability in existing turbulent inflow generation methods, and to provide a turbulent inflow generation method, device, medium, and product based on pulsating velocity renormalization. Compared with the prior art, the method proposed in this invention only depends on the local pulsating velocity and turbulent kinetic energy distribution, can be applied to any configuration, and the generated pulsation contains a self-sustaining coherent structure that will not disappear downstream due to dissipation, resulting in a long lifespan.

[0007] The technical solution of the present invention is as follows:

[0008] A method for generating turbulent inflows based on fluctuating velocity renormalization includes:

[0009] Step S1: Discretize and obtain the turbulent kinetic energy distribution of all discrete grid points on the inlet section. ,or , , Turbulent kinetic energy component in the direction , , ;

[0010] Step S2: Before each iteration of the numerical solution of the flow equation, add random fluctuating velocities to all discrete grid points at the inlet section. ;

[0011] Step S3: [Illegible text - likely related to inlet section] Downstream The area within the distance is defined as Calculate before each numerical iteration The renormalized pulsations of all discrete grid points within the system ;

[0012] Step S4: Calculation The renormalization coefficients of all discrete grid points within the grid;

[0013] Step S5: Restructuring The pulsation velocity of all discrete grid points within the area ;

[0014] Step S6: Update Velocity field of all discrete grid points:

[0015] .

[0016] Furthermore, if step S1 provides a turbulent kinetic energy distribution, then the random fluctuating velocity in step S2... The calculation method is as follows:

[0017]

[0018] If step S1 provides the turbulent kinetic energy component, then the random pulsating velocity in step S2... The calculation method is as follows:

[0019]

[0020] in:

[0021] It is a random number within the interval [-1, 1].

[0022] Furthermore, in step S3 The range of values ​​is , This represents the boundary layer thickness at the inlet section.

[0023] Furthermore, in step S3, the pulse to be reshaped The calculation method is as follows:

[0024]

[0025] in:

[0026] Represents the average velocity over time The average velocity is obtained by performing a spatial spanwise average.

[0027] Furthermore, the time-averaged speed The calculation method is as follows:

[0028]

[0029] in:

[0030] For the first The instantaneous velocity of the flow at the discrete grid points before the next iteration.

[0031] Further, step S4 includes:

[0032] If step S1 provides a turbulent kinetic energy distribution, then the renormalization coefficients... The calculation method is as follows:

[0033]

[0034] If step S1 provides the turbulent kinetic energy component, then the renormalization coefficients of the three velocity components are... The calculation method is as follows:

[0035] .

[0036] Further, step S5 includes:

[0037] If step S1 provides a turbulent kinetic energy distribution, the renormalization method is as follows:

[0038]

[0039] If step S1 provides the turbulent kinetic energy component, the renormalization method is as follows:

[0040] .

[0041] The present invention also proposes an electronic device, comprising:

[0042] At least one processor; and a memory communicatively connected to said at least one processor;

[0043] The memory stores instructions that can be executed by the at least one processor, and the at least one processor executes the instructions stored in the memory to perform the method described above.

[0044] The present invention also proposes a computer-readable storage medium for storing instructions that, when executed, cause the method described above to be implemented.

[0045] The present invention also proposes a computer program product, which implements the above-described method when executed by a processor.

[0046] Compared with existing technologies, the advantages of this invention are:

[0047] This invention eliminates the need for direct simulation of the flow evolution in the upstream region of turbulence, reducing computational overhead. Compared to traditional methods, the scheme provided by this invention utilizes turbulent kinetic energy as the pulsation renormalization criterion, which has more direct physical meaning, and the renormalized pulsation information has a more realistic self-organized coherent structure. Furthermore, this invention does not require extracting pulsation information from the turbulent region, but directly generates random pulsation information that satisfies the turbulent kinetic energy distribution at the turbulent inlet section, making it easier to program and implement. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0049] Figure 1 The turbulent fluctuations generated by this invention and their development downstream;

[0050] Figure 2 This invention provides a comparison between the simulated frictional resistance coefficient obtained by this invention and the momentum-thickness Reynolds number, and the experimental results.

[0051] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0052] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0054] Example 1

[0055] This embodiment proposes a turbulent inflow generation method based on fluctuating velocity renormalization. It utilizes the turbulent kinetic energy distribution to continuously renormalize the fluctuating velocity over a distance downstream of the inflow plane, solving the problems of traditional methods lacking spatial and temporal turbulence-related information and insufficient versatility. It also eliminates the computational overhead of directly simulating the flow evolution in the upstream region of turbulence, reducing programming complexity.

[0056] In this embodiment, specifically, a turbulent inflow generation method based on fluctuating velocity renormalization includes the following steps:

[0057] Step S1: Discretize and obtain the turbulent kinetic energy distribution of all discrete grid points on the inlet section. ,or , , Turbulent kinetic energy component in the direction , , That is, to establish a three-dimensional Cartesian coordinate system. Describe all spatial points within the flow. The inlet section of the turbulent region is represented, and the turbulent kinetic energy distribution of all discrete grid points on the inlet section is discretized. ,or , , Turbulent kinetic energy component in the direction , , ;

[0058] Step S2: Before each iteration of the numerical solution of the flow equation, add random fluctuating velocities to all discrete grid points at the inlet section. ;

[0059] Step S3: [Illegible text - likely related to inlet section] Downstream The area within the distance is defined as Calculate before each numerical iteration The renormalized pulsations of all discrete grid points within the system It should be noted that, The range of values ​​is , This represents the boundary layer thickness at the inlet section;

[0060] Step S4: Calculation The renormalization coefficients of all discrete grid points within the grid;

[0061] Step S5: Restructuring The pulsation velocity of all discrete grid points within the area ;

[0062] Step S6: Update Velocity field of all discrete grid points:

[0063] .

[0064] In this embodiment, specifically, if step S1 provides a turbulent kinetic energy distribution, then the random fluctuating velocity in step S2... The calculation method is as follows:

[0065]

[0066] If step S1 provides the turbulent kinetic energy component, then the random pulsating velocity in step S2... The calculation method is as follows:

[0067]

[0068] in:

[0069] It is a random number within the interval [-1, 1].

[0070] In this embodiment, it should be noted that in step S3, the numerical iteration is calculated before each iteration. The time-averaged velocity of all discrete grid points within the range, with the first... Taking the next iteration as an example, the time average speed The calculation method is as follows:

[0071]

[0072] in:

[0073] For the first The instantaneous velocity of the flow at the discrete grid points before the next iteration;

[0074] Next, the time-averaged velocity is spatially spanwise averaged to obtain... Then calculate the pulse to be renormalized:

[0075]

[0076] in:

[0077] Represents the average velocity over time The average velocity is obtained by performing a spatial spanwise average.

[0078] In this embodiment, specifically, step S4 includes:

[0079] If step S1 provides a turbulent kinetic energy distribution, then the renormalization coefficients... The calculation method is as follows:

[0080]

[0081] If step S1 provides the turbulent kinetic energy component, then the renormalization coefficients of the three velocity components are... The calculation method is as follows:

[0082]

[0083] In this embodiment, specifically, step S5 includes:

[0084] If step S1 provides a turbulent kinetic energy distribution, the renormalization method is as follows:

[0085]

[0086] If step S1 provides the turbulent kinetic energy component, the renormalization method is as follows:

[0087] .

[0088] Based on the same technical concept, embodiments of the present invention also provide an electronic device that can implement the turbulent inflow generation method based on pulsating velocity renormalization provided in the above embodiments of the present invention. In one embodiment, the electronic device can be a server, a terminal device, or other electronic devices. Figure 3 As shown, the electronic device may include:

[0089] At least one processor and a memory connected to the at least one processor. In this embodiment of the invention, the specific connection medium between the processor and the memory is not limited. Figure 3 The example used is the connection between the processor and memory via a bus. The bus... Figure 3 The connections between other components are indicated by thick lines and are for illustrative purposes only, not as limiting information. Buses can be divided into address buses, data buses, control buses, etc., but for ease of representation, [the specific bus type is not shown here]. Figure 3 The processor is represented by a single thick line, but this does not imply that there is only one bus or one type of bus. Alternatively, a processor can also be called a controller; there are no restrictions on the name.

[0090] In this embodiment of the invention, the memory stores instructions executable by at least one processor. By executing the instructions stored in the memory, the at least one processor can execute the turbulent inflow generation method based on pulsating velocity renormalization described above. The processor can implement... Figure 3 The functions of each module in the device shown.

[0091] The processor is the control center of the device. It can connect to various parts of the control device through various interfaces and lines. By running or executing instructions stored in memory and calling data stored in memory, it can monitor the device's various functions and process data, thereby enabling overall monitoring of the device.

[0092] In an alternative design, the processor may include one or more processing units. The processor may integrate an application processor and a modem processor, wherein the application processor primarily handles the operating system, user interface, and applications, while the modem processor primarily handles wireless communication. It is understood that the modem processor may also not be integrated into the processor. In some embodiments, the processor and memory may be implemented on the same chip; in some embodiments, they may also be implemented separately on separate chips.

[0093] The processor can be a general-purpose processor, such as a CPU, digital signal processor, application-specific integrated circuit, field-programmable gate array or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, capable of implementing or executing the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the turbulent inflow generation method based on pulsating velocity renormalization disclosed in the embodiments of this invention can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0094] Memory, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. Memory can include at least one type of storage medium, such as flash memory, hard disk, multimedia cards, card-type memory, random access memory (RAM), static random access memory (SRAM), programmable read-only memory (PROM), read-only memory (ROM), and electrically erasable programmable read-only memory (EPROM). Only memory (EEPROM), magnetic storage, magnetic disks, optical disks, etc. A memory is any other medium capable of carrying or storing desired program code in the form of instructions or data structures, and accessible by a computer, but is not limited thereto. The memory in embodiments of this invention can also be a circuit or any other device capable of performing storage functions for storing program instructions and / or data.

[0095] By designing and programming the processor, the code corresponding to the turbulent inflow generation method based on pulsating velocity renormalization described in the foregoing embodiments can be embedded into the chip, thereby enabling the chip to execute the steps of the method described in the foregoing embodiments during runtime. How to design and program the processor is a technique well-known to those skilled in the art and will not be elaborated upon here.

[0096] Based on the same inventive concept, embodiments of the present invention also provide a storage medium storing computer instructions that, when executed on a computer, cause the computer to perform a turbulent inflow generation method based on pulsating velocity renormalization as described above.

[0097] In some alternative embodiments, the present invention also provides a method for generating turbulent inflows based on pulsating velocity renormalization, which can also be implemented as a program product including program code that, when the program product is run on a device, causes the control device to perform the steps in the method for generating turbulent inflows based on pulsating velocity renormalization according to various exemplary embodiments of the present invention as described above.

[0098] It should be noted that although several units or sub-units of the apparatus have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the invention, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units. Furthermore, although the operation of the method of the invention is described in a specific order in the drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0099] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can be implemented in one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs) containing computer-usable program code. The form of a computer program product implemented on ROM, optical memory, etc.

[0100] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a server, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0101] Program code for performing the operations of this invention can be written using any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0102] In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0103] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0104] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0105] Furthermore, in some embodiments, a computer program product is also proposed, which, when executed by a processor, implements the above-described turbulent inflow generation method based on pulsating velocity renormalization.

[0106] Example 2

[0107] Example 2 applies the turbulent inflow generation method based on fluctuating velocity renormalization proposed in Example 1 to the generation of fluctuating quantities at the inlet section of the turbulent region in a flat plate turbulent boundary layer, with a Reynolds number of [missing information]. The corresponding direct numerical simulation results are referenced in "Schlatter & Orlu, Assessment of direct numerical simulation data of turbulent boundary layers, JFM. 2010, vol. 659, pp. 116-126." Figure 1 As can be seen from the turbulent pulsations generated by this invention and their development downstream, a turbulent coherent structure is rapidly generated in the pulsation correction region with a boundary layer thickness of one downstream of the inlet. Furthermore, downstream of the correction region, the flow structure does not decay but immediately generates a turbulent boundary layer coherent structure. Figure 2The simulation results of the frictional drag coefficient as a function of momentum, thickness, and Reynolds number are compared with experimental results. It can be seen that, except for the inflow generation region near the inlet, the frictional drag coefficient given in this invention maintains an error of less than 5% compared with the experimental results.

[0108] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0109] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for generating a turbulent inflow based on a pulsating velocity reshaping, characterized in that, Comprising: Step S1 : Discretely give the distribution of turbulent kinetic energy of all discrete grid points on the inlet section , or , , component of turbulent kinetic energy in the direction , , ; Step S2: Add random fluctuating velocities to all discrete grid points in the inlet section before each iteration of the numerical solution of the flow equations ; Step S3: the inlet cross section downstream The region within the distance is defined as , the to-be-rebalanced fluctuation of all discrete grid points in the region is calculated before each numerical iteration ;​ Step S4: Calculate renormalization coefficients for all discrete grid points within the inner region; Step S5: reforming fluctuation velocity of all discrete grid points inside ; Step S6: Update Velocity field at all discrete grid points: The pulse to be reshaped in step S3 The calculation method is as follows: wherein: denotes the time-averaged velocity the average velocity obtained by spatial span-wise averaging The step S4 comprises: If the step S1 gives the distribution of turbulent kinetic energy, the calculation method of the reformation coefficient is as follows: If the step S1 gives the turbulent kinetic energy component, the reformation coefficient of the 3-direction velocity component is calculated as follows: The step S5 comprises: If the step S1 gives a turbulent kinetic energy distribution, the regularization method is: If the step S1 gives a turbulent kinetic energy component, the regularization method is: 。 2. A method of generating a turbulent inflow based on the pulsating velocity reshaping according to claim 1, characterized in that, If the step S1 gives the turbulent kinetic energy distribution, the calculation method of the random fluctuation velocity in the step S2 is: If the step S1 gives the turbulent kinetic energy component, the calculation method of the random fluctuation velocity in the step S2 is: wherein: is a random number in the interval [-1, 1].

3. A method of generating a turbulent inflow based on the pulsating velocity reshaping according to claim 2, characterized in that, The value range of the step S3 The value range of the step S3 , represents the boundary layer thickness at the inlet cross section.

4. A method of generating a turbulent inflow based on the pulsating velocity reshaping according to claim 3, characterized in that, Time-averaged velocity The calculation method is: wherein: For the first iteration, the instantaneous velocity of the flow at the discrete grid points is taken to be the steady-state velocity.

5. An electronic device, comprising: Comprising: at least one processor; and a memory connected with the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the at least one processor, by executing the instructions stored in the memory, causes the at least one processor to perform the method of any one of claims 1-4.

6. A computer readable storage medium characterized by, The computer readable storage medium is used to store instructions, when the instructions are executed, the method of any one of claims 1-4 is realized.

7. A computer program product, characterised in that, The computer program is executed by the processor to realize the method of any one of claims 1-4.

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