Foundation scour fluid-solid-soil coupling simulation method based on sph-dem coupling and multiphase flow theory

Patent metadata

Field	Value
Publication number	US-2024256740-A1
Application number	US-202218546570-A
Country	US
Kind code	A1
Filing date	Dec 28, 2022
Priority date	Nov 11, 2022
Publication date	Aug 1, 2024
Grant date	—

Abstract

The present disclosure discloses a foundation scour fluid-solid-soil coupling simulation algorithm based on SPH-DEM coupling and a multiphase flow theory, including: constructing a particle model, setting fluid particles and bed material particles based on the multiphase flow theory, and setting rigid particles based on a DEM theory; correcting a fluid control equation based on a fluid-solid coupling theory, and solving governing equations of the fluid particles; solving governing equations of DEM rigid particles by introducing fluid-solid coupling force, introducing fluid-soil and soil-solid coupling force to correct a sediment incipient motion model, based on a sediment Shield criterion, and solving foundation scour governing equations; and finishing a time step and entering next cycle. The present disclosure introduces a plurality of structure and state models through secondary development based on the SPH-DEM coupling and the multiphase flow theory, thereby realizing refined numerical simulation of foundation scour fluid-solid-soil coupling.

First claim

What is claimed is:

1 . A foundation scour fluid-solid-soil coupling simulation method based on SPH-DEM coupling and a multiphase flow theory, comprising following steps:
step 1: constructing a particle model, setting fluid particles and bed material particles based on the multiphase flow theory, and setting rigid particles based on a DEM theory, specific steps comprising as below: step 1.1: respectively constructing a fluid particle model and a soil particle model based on a multiphase flow basic principle, setting the fluid particle model as Newtonian fluid, setting the soil particle model as non-Newtonian fluid, and determining a soil viscosity μ HBP based on an HBP model,

μ
HBP

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τ
c

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II
D

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1
-

e

m
⁢

II
D

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+

2
⁢
μ
⁢

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4
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II
D

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n
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1

2

wherein τ c denotes yield stress of a model material, II D denotes a second invariant of a fluid strain rate tensor, m denotes a stress exponent growth coefficient, μ denotes a water viscosity, and n denotes an exponent associated with shear stress;
step 1.2: introducing a DP yield criterion to calculate specific material yield stress τ y ;
step 1.3: substituting the specific material yield stress τ y obtained in step 1.2 into the calculation formula of the soil viscosity μ HBP in step 1.1 to replace the model material yield stress τ c , and establishing a soil viscosity calculation model;
step 1.4: setting the rigid particles based on the DEM theory, and determining a normal contact rigidity K n , normal contact damping γ n , a tangential contact rigidity K t and tangential contact damping γ t among the rigid particles; and
step 1.5: calculating normal contact force F, and tangential contact force F, based on the normal contact rigidity K n , the normal contact damping γ n , the tangential contact rigidity K t and the tangential contact damping γ t among the rigid particles obtained in step 1.4;
step 2: introducing a fluid-solid coupling theory based on the particle model obtained in step 1 to correct a fluid control equation, and performing controlled solving of the fluid particles, specific steps comprising as below:
step 2.1: introducing particle fluid-solid coupling force F fs , and correcting a fluid momentum conservation equation; and
step 2.2: giving a discrete form of the fluid momentum conservation equation obtained in step 2.1, based on a kernel function theory of an SPH algorithm;
step 3: based on the particle model obtained in step 1, correcting and solving the rigid particle control equation by combining the Newton's second law and considering the particle fluid-solid coupling force F fs obtained in step 2;
step 4: based on the particle model obtained in step 1, introducing a sediment particle Shield criterion, correcting a sediment incipient motion model in combination with the fluid-soil coupling force obtained in step 1 and the solid-soil coupling force obtained in step 2, and performing foundation scour controlled solving, specific steps comprising as below:
step 4.1: based on the fluid particle velocity μ obtained based on the momentum equation in step 2, introducing an Einstein logarithmic flow velocity distribution formula to calculate fluid shear stress τ b exerted on soil particles;
step 4.2: based on the soil particle viscosity μ HBP model obtained in step 1.1, introducing the sediment particle Shield criterion to calculate sediment incipient motion critical stress τ cr,0 ;
step 4.3: based on the sediment incipient motion critical stress τ cr,0 obtained in step 4.2, introducing the fluid-solid coupling force F fs of the sediment particles and the rigid particles obtained in step 2 to calculate corrected sediment incipient motion critical stress τ cr considering an external load and a side slope effect;
step 4.4: judging the incipient motion state of the sediment particles based on the fluid shear stress τ b obtained in step 4.1 and the corrected sediment incipient motion critical stress τ cr obtained in step 4.3, wherein if τ cr <TD is satisfied, τ cr is substituted into the formula in step 1.1 to replace the yield stress τ c , a bed material particle viscosity μ HBP is updated to make the bed material particle into a bed load particle, and if the condition is not satisfied, processing is performed according to step 1.2 and step 1.3;
step 4.5: according to the bed load particles obtained in step 4.4, introducing a Mastbergen formula to calculate a critical flow velocity μ lift at which a bed load is converted into a suspended load, wherein if a flow velocity μ≥μ lift of the fluid particles is satisfied, the fluid particles are converted into suspended load particles, and an equivalent viscosity μ lift is calculated to replace the bed material particle viscosity μ HBP , and if the condition is not satisfied, no processing is performed; and
step 4.6: according to the suspended load particles obtained in step 4.5, introducing the Mastbergen formula to calculate a critical flow velocity μ set at which the suspended load is converted into the bed load, wherein if the actual flow velocity us μ set of the particles is satisfied, the particles are converted into the bed load particles and processed according to step 4.4, and if the condition is not satisfied, no processing is performed; and
step 5: repeating step 1 to step 4 until solving is completed.

2 . The foundation scour fluid-solid-soil coupling simulation method based on the SPH-DEM coupling and the multiphase flow theory according to claim 1 , wherein in step 1.2, the material yield stress τ y is calculated as below:

Assignees

• Univ Southeast

Inventors

• Xiong Wen
• Zhang Rongzhao

Classifications

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G06F17/11

  for solving equations {, e.g. nonlinear equations, general mathematical optimization problems (optimization specially adapted for a specific administrative, business or logistic context G06Q10/04)} · CPC title

• G06F30/28

  using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD] · CPC title

• G06F30/25 Primary

  using particle-based methods · CPC title

• G06F2111/10

  Numerical modelling · CPC title