CN-122021465-A - Method for determining porous medium resistance coefficient of permeable building in CFD numerical simulation

Abstract

The invention discloses a method for determining porous medium resistance coefficients of a permeable building in CFD numerical simulation, which comprises the steps of adopting a series of physical model tests to measure upstream and downstream water depths and flow velocities of the permeable building under a given incoming flow condition and obtain hydraulic characteristics of the permeable building under different geometric scales, adopting the CFD numerical simulation to invert the physical model tests of different geometric scales, adopting the porous medium to simulate the permeable building in the CFD model, adopting a Forchheimer-form resistance formula to calculate the resistance of the porous medium to water flow and obtain the resistance characteristics of the permeable building, establishing mathematical relations between viscous resistance coefficients and inertia resistance coefficients and the geometric scales, and determining the viscous resistance coefficients and the inertia resistance coefficients of a prototype scale and other unknown scales. The method improves the accuracy of the resistance coefficient of the porous medium of the permeable building, and is suitable for the permeable building in submerged and water-out forms consisting of different porous or open structures.

Inventors

• SUN BO
• LI JIANMIN
• WU JIN
• XIAO KAI
• XU JIANGANG
• DAI PENG
• LI CHANGLIANG
• WU MINGZHEN
• HE ZHICHAO
• ZHANG BO
• YANG WENBIN
• YU YONG
• CHEN JIEZHI
• GAO YUNFENG
• Zhao Houzhi
• HAO LEI
• YU CHENGYU
• LI BOWEN
• WANG XUCHEN
• LI XIAOJIAN
• ZHANG QIFENG
• LI KUN
• JI ZEZHOU
• SUN LINYUN
• CHEN DAKE
• ZHANG GUANGLEI
• TANG LEI
• LI ZHENQIANG
• Wang Ningge

Assignees

• 水利部交通运输部国家能源局南京水利科学研究院
• 唐山港口实业集团有限公司
• 中交第一航务工程勘察设计院有限公司

Dates

Publication Date

20260512

Application Date

20260410

Claims (8)

1. 1. The method for determining the porous medium resistance coefficient of the permeable building in CFD numerical simulation is characterized by comprising the following steps of: Step 1, aiming at a permeable building which is required to be researched and consists of a plurality of porous or open structures, acquiring the section size of the permeable building and the size of a single porous or open structure; Step 2, determining n normal geometric scales in a water permeable building section through-flow water tank test according to the cross section size of the water permeable building, the size of a single porous or open structure body, the water tank size and the flow making capacity; Step 3, determining the cross section size of the permeable building and the size of a single porous or open structure body under the condition of normal geometric proportion, and manufacturing a plurality of test structure bodies under the condition of normal geometric proportion; Step 4, designing a water-permeable building section flowing water trough test under the condition of normal geometric scale, wherein the test groups under each scale are m groups, and setting the water depth and the average flow velocity or the water depth and the flow of each group of test; Step 5, carrying out a water-permeable building section flowing water tank test under the condition of normal geometric proportion; step 6, carrying out a water trough test of the cross section overcurrent CFD value of the permeable building under the condition of each normal geometric scale, and calculating the resistance of the porous medium to water flow by adopting a Forchheimer-form resistance formula to obtain the resistance coefficients of the porous medium under all normal geometric scales, wherein the resistance coefficients comprise a viscous resistance coefficient A and an inertial resistance coefficient B; Step 7, establishing mathematical relations between the viscous drag coefficient A and the inertia drag coefficient B and the normal geometric scale according to the obtained porous medium drag coefficients of the permeable building under different normal geometric scale conditions; And 8, calculating a viscous drag coefficient A and an inertial drag coefficient B which are aimed by the prototype scale and other unknown normal geometric scales according to the mathematical relationship.
2. 2. The method for determining the resistance coefficient of porous media of water permeable building according to claim 1, wherein in the step 1, the porous or open structure body comprises a water permeable frame, a hollow block body, a solar block body and a hook connection body.
3. 3. The method for determining the resistance coefficient of porous media of a permeable building according to claim 1, wherein in the step 2, n normal geometric scales are respectively lambda 1 ,λ 2 ,λ 3 ,…,λ n , and 5-6 rows of holes or open structures are arranged in the width direction of the water tank when the geometric scales are designed.
4. 4. The method for determining the resistance coefficient of porous media of water permeable building according to claim 1, wherein in the step 3, the test structure body is made of concrete or weight-increasing plastic.
5. 5. The method for determining the resistance coefficient of porous media of permeable building according to claim 1, wherein in the step 4, if the permeable building is a non-submerged building, the water depth in the water tank test is smaller than the top elevation of the permeable building, and if the permeable building is a submerged building, the water depth in the water tank test is greater than the top elevation of the permeable building.
6. 6. The method for determining the resistance coefficient of porous media of a permeable building according to claim 1, wherein in the step 5, a normal geometric scale λ i , i=1, 2,3, and n is performed, and the specific steps are as follows: Step 5.1, manufacturing a permeable building in a water tank test section by using a test structure body under the condition of a normal geometric proportion rule lambda i according to the section size of the permeable building after the shrinkage, wherein the permeable building occupies the whole water tank width, the water tank width direction is the section of the permeable building, and the arrangement mode of the structure body is consistent with that in actual production; Step 5.2, carrying out the water tank test designed in the step 4 in a water tank, and measuring the upstream stable section water depth h 1j , the section average flow speed u 1j , the downstream stable section water depth h 2j and the section average flow speed u 2j of the permeable building for each group of tests, wherein j is the mark of different groups, j=1, 2, 3; And 5.3, repeating the steps 5.1 and 5.2, and completing the water-permeable building section water flowing trough test of all normal geometric proportion scales.
7. 7. The method for determining the resistance coefficient of porous media of a permeable building according to claim 6, wherein in the step6, a permeable building section overcurrent CFD numerical water tank test under the condition of a normal geometric ratio rule lambda i is performed, and the specific steps are as follows: Step 6.1, selecting one scale from normal geometric scales to carry out CFD numerical water tank test, establishing a CFD numerical water tank consistent with the range of a physical water tank, wherein an upstream boundary adopts a flow or flow velocity boundary, a downstream boundary adopts a pressure boundary, a side boundary adopts a symmetrical boundary, the top is an air pressure boundary, a bottom boundary is a side wall boundary, a slip-free condition is adopted, a numerical model simulates a permeable building by adopting a porous medium method, and the size of the permeable building is the same as that of a permeable building in the physical water tank under the same normal geometric scale; Step 6.2, inverting the physical water tank test under the corresponding normal geometric proportion rule condition developed in the step 5.2 by utilizing a CFD numerical water tank, and simulating porous medium resistance coefficients of the permeable building by adjusting CFD numerical water tanks in each group of water tank tests, so that the water depth section average flow velocity of a downstream stable section in the numerical water tank is identical with the water depth h 2j and the section average flow velocity u 2j of the downstream stable section of the physical water tank under the conditions of the upstream stable section of the permeable building and the section average flow velocity u 1j , thereby obtaining porous medium resistance coefficients of the permeable building under the corresponding normal geometric proportion rule condition, including a viscous resistance coefficient A i and an inertial resistance coefficient B i ; and 6.3, repeating the steps 6.1 and 6.2 to finish the water permeable building section overcurrent CFD numerical water tank test of all normal geometric scales, and obtaining the porous medium resistance coefficient under all normal geometric scales.
8. 8. The method for determining porous medium resistance coefficient of permeable building according to claim 7, wherein in the step 6, the porous medium resistance of permeable building in CFD numerical simulation adopts a resistance formula in Forchheimer, and the resistance is the sum of a primary term and a secondary term of microscopic flow velocity of the porous medium region: ; wherein: Is porous medium resistance; in the form of a viscous drag force term, Is an inertial resistance term; Microscopic flow rates for porous media regions; is the fluid density; Is apparent flow rate; And Is the porosity of the permeable building Is a function of (2); And The viscous drag coefficient and the inertial drag coefficient, respectively.

Description

Method for determining porous medium resistance coefficient of permeable building in CFD numerical simulation Technical Field The invention relates to the technical field of numerical simulation of water conservancy, water transportation and ocean engineering, in particular to a method for determining a porous medium resistance coefficient of a permeable building in CFD numerical simulation. Background The permeable building has a certain permeability rate due to larger porosity, is beneficial to water body exchange, dissipates wave energy and enhances ecological effect, and is widely applied to the projects of a bunk dam, a bank and beach, a sea wall and a breakwater in recent years. Through CFD numerical simulation, the surrounding flow field characteristics of the wading building are analyzed, the section design and plane layout of the wading building are optimized, and the method is an important way for developing wading building research in water conservancy, water transportation and ocean engineering. Because the permeable building generally consists of porous or open structures such as permeable frames, hollow blocks, hook connection bodies and the like, the whole structure is complex, and challenges such as small grids, huge calculation amount and the like are faced to carrying out CFD numerical simulation calculation by directly describing the form of the permeable building. Porous media methods are currently commonly used to simulate water permeable buildings. When the method is used for simulating the permeable building, determining the reasonable porous medium resistance coefficient is a key for accurately simulating the hydraulic characteristic of the permeable building. Disclosure of Invention The invention aims to solve the problems of providing a method for determining the porous medium resistance coefficient of a permeable building in CFD numerical simulation, which realizes the determination of the porous medium resistance coefficient of the permeable building with different scales through a water tank test, numerical inversion and resistance coefficient regression, lays a foundation for accurately simulating the hydraulic characteristics of the permeable building, and provides a reliable basis for engineering design. The invention adopts the following technical scheme that the method for determining the porous medium resistance coefficient of the permeable building in CFD numerical simulation comprises the following steps: step 1, aiming at a permeable building which is required to be researched and consists of a plurality of porous or open structures (such as a permeable frame, a hollow block, a Chinese character 'ri' block and a hook connected body), acquiring the section size of the permeable building and the size of a single porous or open structure; Step 2, determining n normal geometric scales in a water permeable building section through-flow water tank test according to the cross section size of the water permeable building, the size of a single porous or open structure body, the water tank size and the flow making capacity; Step 3, determining the cross section size of the permeable building and the size of a single porous or open structure body under the condition of normal geometric proportion, and manufacturing a plurality of test structure bodies under the condition of normal geometric proportion; Step 4, designing a water-permeable building section flowing water trough test under the condition of normal geometric scale, wherein the test groups under each scale are m groups, and setting the water depth and the average flow velocity or the water depth and the flow of each group of test; Step 5, carrying out a water-permeable building section flowing water tank test under the condition of normal geometric proportion; step 6, carrying out a water trough test of the cross section overcurrent CFD value of the permeable building under the condition of each normal geometric scale, and calculating the resistance of the porous medium to water flow by adopting a Forchheimer-form resistance formula to obtain the resistance coefficients of the porous medium under all normal geometric scales, wherein the resistance coefficients comprise a viscous resistance coefficient A and an inertial resistance coefficient B; Step 7, establishing mathematical relations between the viscous drag coefficient A and the inertia drag coefficient B and the normal geometric scale lambda according to the porous medium drag coefficients (the viscous drag coefficient A and the inertia drag coefficient B) of the permeable building under the different normal geometric scales obtained in the step 6; And 8, calculating a viscous drag coefficient A and an inertial drag coefficient B aiming at the prototype scale (namely, the normal geometric scale is 1) and other unknown normal geometric scales according to the mathematical relation established in the step 8. In step 2, n normal geometric scales are respectively lambd