RD-E: 0601 Fluid Structure Coupling

Sloshing inside a fuel tank by simulating the fluid structure coupling. The tank deformation is achieved by applying an imposed velocity on the left corners. Water and air inside the tank are modeled with the ALE formulation. The tank container is described using a Lagrangian formulation.

A numerical simulation of fluid-structure coupling is performed on sloshing inside a deformable fuel tank. This example uses the ALE (Arbitrary Lagrangian Eulerian) formulation and the hydrodynamic bi-material law (/MAT/LAW37) to model interaction between water, air and the tank container.

Options and Keywords Used

  • Fluid structure coupling simulation, and ALE formulation
  • Shell and brick elements
  • Hydrodynamic and bi-phase liquid gas material (/MAT/LAW37 (BIPHAS))
  • ALE boundary conditions (/ALE/BCS)
  • J. Donea Grid Formulation (/ALE/GRID/DONEA)
  • Boundary conditions (/BCS)
  • Gravity (/GRAV)
  • Imposed velocity (/IMPVEL)
  • ALE material formulation (/ALE/MAT)
Velocities (/IMPVEL) are imposed on the left corners in the X direction.
Table 1. Imposed Velocity versus Time Curve
Velocity (ms-1) 0 5 0 0
Time (ms) 0 12 12.01 50

rad_ex_fig_6-4
Figure 1. Kinematic Condition: Imposed Velocities
Regarding the ALE boundary conditions, constraints are applied on:
  • Material velocity
  • Grid velocity

All nodes, except those on the border have grid (/ALE/BCS) and material (/BCS) velocities fixed in the Z-direction. The nodes on the border only have a material velocity (/BCS) fixed in the Z-direction.

Both the ALE materials air and water must be declared ALE using /ALE/MAT.
Note: Lagrangian material is automatically declared Lagrangian.

The /ALE/GRID/DONEA option activates the J. Donea grid formulation to compute the grid velocity. See the Radioss Theory Manual for further explanations about this option.

Input Files

Refer to Access the Model Files to download the required model file(s).

The model files used in this example include:

TANK_*.rad

Model Description

A rectangular tank made of steel is partially filled with water, the remainder being supplemented by air. The initial distribution pressure is known and supposed homogeneous. The tank container dimensions are 460 mm x 300 mm x 10 mm, with thickness being at 2 mm.

Deformation of the tank container is generated by an impulse made on the left corners of the tank for analyzing the fluid-structure coupling.

rad_ex_6-1
Figure 2. Problem Description
The steel container is modeled using the elasto-plastic model of Johnson-Cook law (/MAT/LAW2) with the following parameters:
Material Properties
Density
0.0078 [gmm3] MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaadaWcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Young's modulus
210000 [MPa] MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaaiGac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Poisson's ratio
0.29
Yield stress
180 [MPa] MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaaiGac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Hardening parameter
450 [MPa] MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaaiGac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Hardening exponent
0.5

The material air-water bi-phase is described in the hydrodynamic bi-material liquid-gas law (/MAT/LAW37). Material LAW37 is specifically designed to model bi-material liquid gas.

The equations used to describe the state of viscosity and pressure are:
Viscosity
Sij=2ρve˙ij MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGtbWaaSbaaSqaaiaadMgacaWGQbaabeaakiabg2da9iaaikdacqaHbpGCcaWG2bGabmyzayaacaWaaSbaaSqaaiaadMgacaWGQbaabeaaaaa@40C2@
σkk=λε˙kk MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHdpWCdaWgaaWcbaGaam4AaiaadUgaaeqaaOGaeyypa0Jaeq4UdWMafqyTduMbaiaadaWgaaWcbaGaam4AaiaadUgaaeqaaaaa@40AD@
Liquid EOS
Pl=P0+Clμ MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbWaaSbaaSqaaiaadYgaaeqaaOGaeyypa0JaamiuamaaBaaaleaacaaIWaaabeaakiabgUcaRiaadoeadaWgaaWcbaGaamiBaaqabaGccqaH8oqBaaa@3FAC@
Where, Cl=ρ0l(c0l)2 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaapeGaam4qa8aadaWgaaWcbaWdbiaadYgaa8aabeaak8qacqGH9aqpcqaHbpGCpaWaa0baaSqaaiaaicdaaeaacaWGSbaaaOWaaeWaaeaapeGaam4ya8aadaqhaaWcbaGaaGimaaqaaiaadYgaaaaakiaawIcacaGLPaaadaahaaWcbeqaaiaaikdaaaaaaa@424B@ and μ=ρρ01 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaapeGaeqiVd0Maeyypa0ZaaSaaaeaacqaHbpGCaeaacqaHbpGCdaWgaaWcbaGaaGimaaqabaaaaOGaeyOeI0IaaGymaaaa@3EF0@
Gas EOS
Pvγ=P0v0γ=constant MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaapeGaamiuaiaadAhapaWaaWbaaSqabeaapeGaeq4SdCgaaOGaeyypa0Jaamiua8aadaWgaaWcbaWdbiaaicdaa8aabeaak8qacaWG2bWdamaaDaaaleaapeGaaGimaaWdaeaapeGaeq4SdCgaaOGaeyypa0Jaam4yaiaad+gacaWGUbGaam4CaiaadshacaWGHbGaamOBaiaadshaaaa@494B@
Where, v=VV0 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbba9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaapeGaamODaiabg2da9maalaaabaGaamOvaaqaaiaadAfadaWgaaWcbaGaaGimaaqabaaaaaaa@3AB9@ as special volume

The equilibrium is defined by: ΔPl=ΔPg MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqqHuoarcaWGqbWaaSbaaSqaaiaadYgaaeqaaOGaeyypa0JaeuiLdqKaamiuamaaBaaaleaacaWGNbaabeaaaaa@3E19@

Where,
Sij
Deviatoric stress tensor
eij
Deviatoric strain tensor
Material Parameters - For Liquid
Liquid reference density, ρl0
0.001 [gmm3] MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaadaWcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Liquid bulk modulus, Cl
2089 N/mm2
Initial mass fraction liquid proportion, al
100%
Shear kinematic viscosity νl MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH9oGBdaWgaaWcbaGaamiBaaqabaaaaa@3934@ , =μ/ρ0l MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpcqaH8oqBcaGGVaGaeqyWdi3aa0baaSqaaiaaicdaaeaacaWGSbaaaaaa@3D66@
0.001 mm2/ms
Material Parameters - For Gas
Gas reference density, ρ0g MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHbpGCdaqhaaWcbaGaaGimaaqaaiaadEgaaaaaaa@39F2@
1.22x10-6 [gmm3] MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaadaWcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Shear kinematic viscosity νg, =μ/ρ0g MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpcqaH8oqBcaGGVaGaeqyWdi3aa0baaSqaaiaaicdaaeaacaWGNbaaaaaa@3D61@
0.00143 mm2/ms
Constant perfect gas, γ
1.4
Initial pressure reference gas, P0
0.1 N/mm2
The main solid TYPE14 properties for air/water parts are:
Properties
Quadratic bulk viscosity/linear bulk viscosity
10-20
Hourglass bulk coefficient
10-5

Model Method

Air and water are modeled using the ALE formulation and the bi-material law (/MAT/LAW37). The tank container uses a Lagrangian formulation and an elasto-plastic material law (/MAT/LAW2).

rad_ex_fig_6-8
Figure 3. Air and Water Mesh (ALE brick elements)

rad_ex_fig_6-3
Figure 4. Tank Container Mesh (shell elements)

Using the ALE formulation, the brick mesh is only deformed by tank deformation the water flowing through the mesh. The Lagrangian shell nodes still coincide with the material points and the elements deform with the material: this is known as a Lagrangian mesh. For the ALE mesh, nodes on the boundaries are fixed in order to remain on the border, while the interior nodes are moved.

Results

Curves and Animations

Fluid - Structure Coupling

ex6_x_momentum_variation
Figure 5. X-Momentum Variation for Each Part
Kinematic conditions generate oscillations of the structure.

ex6_density_attached_variation
Figure 6. Density Attached to the Various Brick Elements
Table 2. Fluid Structure Coupling - Time = 0 ms
Density

density-0_zoom66

Velocity

velocity-0_zoom61

Table 3. Fluid Structure Coupling - Time = 12 ms
Density

density-12_zoom64

Velocity

velocity-12_zoom62

Table 4. Fluid Structure Coupling - Time = 42 ms
Density

density-42_zoom55

Velocity

velocity-42_zoom62