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)
  • Boundary conditions (/BCS)
  • Gravity (/GRAV)
  • Imposed velocity (/IMPVEL)
  • ALE property formulation with Iale = 1
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.

By default, the J. Donea grid formulation is used in Radioss to compute the grid velocity when ALE is activated. Refer to the Radioss Theory Manual for further explanations about this option.

Input Files

Before you begin, copy the file(s) used in this example to your working directory.

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 to be 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
Value
Density
0.0078 [ g m m 3 ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada WcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Young's modulus
210000 [ MPa ] MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9 vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr 0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaai Gac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Poisson's ratio
0.29
Yield stress
180 [ MPa ] MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9 vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr 0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaai Gac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Hardening parameter
450 [ MPa ] MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9 vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr 0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWadaqaai Gac2eacaGGqbGaaiyyaaGaay5waiaaw2faaaaa@3BE6@
Hardening exponent
0.5

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

The equations used to describe the state of viscosity and pressure are:
Viscosity
S ij =2ρv e ˙ ij MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGtbWaaS baaSqaaiaadMgacaWGQbaabeaakiabg2da9iaaikdacqaHbpGCcaWG 2bGabmyzayaacaWaaSbaaSqaaiaadMgacaWGQbaabeaaaaa@40C2@
σ kk =λ ε ˙ kk MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHdpWCda WgaaWcbaGaam4AaiaadUgaaeqaaOGaeyypa0Jaeq4UdWMafqyTduMb aiaadaWgaaWcbaGaam4AaiaadUgaaeqaaaaa@40AD@
Liquid EOS
P l = P 0 + C l μ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbWaaS baaSqaaiaadYgaaeqaaOGaeyypa0JaamiuamaaBaaaleaacaaIWaaa beaakiabgUcaRiaadoeadaWgaaWcbaGaamiBaaqabaGccqaH8oqBaa a@3FAC@
Where, C l = ρ 0 l ( c 0 l ) 2 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape Gaam4qa8aadaWgaaWcbaWdbiaadYgaa8aabeaak8qacqGH9aqpcqaH bpGCpaWaa0baaSqaaiaaicdaaeaacaWGSbaaaOWaaeWaaeaapeGaam 4ya8aadaqhaaWcbaGaaGimaaqaaiaadYgaaaaakiaawIcacaGLPaaa daahaaWcbeqaaiaaikdaaaaaaa@424B@ and μ= ρ ρ 0 1 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape GaeqiVd0Maeyypa0ZaaSaaaeaacqaHbpGCaeaacqaHbpGCdaWgaaWc baGaaGimaaqabaaaaOGaeyOeI0IaaGymaaaa@3EF0@
Gas EOS
P v γ = P 0 v 0 γ =constant MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape GaamiuaiaadAhapaWaaWbaaSqabeaapeGaeq4SdCgaaOGaeyypa0Ja amiua8aadaWgaaWcbaWdbiaaicdaa8aabeaak8qacaWG2bWdamaaDa aaleaapeGaaGimaaWdaeaapeGaeq4SdCgaaOGaeyypa0Jaam4yaiaa d+gacaWGUbGaam4CaiaadshacaWGHbGaamOBaiaadshaaaa@494B@
Where, v = V V 0 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaabaaaaaaaaape GaamODaiabg2da9maalaaabaGaamOvaaqaaiaadAfadaWgaaWcbaGa aGimaaqabaaaaaaa@3AB9@ as special volume

The equilibrium is defined by: Δ P l =Δ P g MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqqHuoarca WGqbWaaSbaaSqaaiaadYgaaeqaaOGaeyypa0JaeuiLdqKaamiuamaa BaaaleaacaWGNbaabeaaaaa@3E19@

Where,
S i j
Deviatoric stress tensor
e i j
Deviatoric strain tensor
Material Parameters - For Liquid
Value
Liquid reference density, ρ l 0
0.001 [ g m m 3 ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada WcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Liquid bulk modulus, C l
2089 N/mm2
Initial mass fraction liquid proportion, a l
100%
Shear kinematic viscosity ν l MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH9oGBda WgaaWcbaGaamiBaaqabaaaaa@3934@ , =μ/ ρ 0 l MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpcq aH8oqBcaGGVaGaeqyWdi3aa0baaSqaaiaaicdaaeaacaWGSbaaaaaa @3D66@
0.001 mm2/ms
Material Parameters - For Gas
Value
Gas reference density, ρ 0 g MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHbpGCda qhaaWcbaGaaGimaaqaaiaadEgaaaaaaa@39F2@
1.22x10-6 [ g m m 3 ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada WcaaqaaiaadEgaaeaacaWGTbGaamyBamaaCaaaleqabaGaaG4maaaa aaaakiaawUfacaGLDbaaaaa@3BBC@
Shear kinematic viscosity ν g , =μ/ ρ 0 g MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpcq aH8oqBcaGGVaGaeqyWdi3aa0baaSqaaiaaicdaaeaacaWGNbaaaaaa @3D61@
0.00143 mm2/ms
Constant perfect gas, γ
1.4
Initial pressure reference gas, P 0
0.1 N/mm2
The main solid TYPE14 properties for air/water parts are:
Properties
Value
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 of 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 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
density-0_zoom66 Figure 7. Fluid Structure Coupling - Time = 0 ms
density-12_zoom64 Figure 8. Fluid Structure Coupling - Time = 12 ms
density-42_zoom55 Figure 9. Fluid Structure Coupling - Time = 42 ms