Kratos 3D FSI Analysis Tutorial Pooyan Dadvand Pavel Ryzhakov Kratos Team

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Partitioned FSI in Kratos P. Dadvand, P. Ryzhakov

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques We have to prepair each subdomain separately - First – structure - Second – fluid

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques STRUCTURE PREPARATION

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques STRUCTURE PREPARATION Load the model: open the structure part model fsi_model_str.gid the geometry will appear Load the problem type: Data->Problem Type: fsi_structure Choose: Update to a new Problem Type

Assign the boundary conditions: 1) Zero DISPLACEMENT at the base (bottom)‏ Fsi Structure->Nodal Values->DISPLACEMENT (on surface): D_x=0.0; V_y=0.0, V_z=0.0 (tick: is_fixed) After assigning the DISPLACEMENT, click: Draw to check that the DISPL is assigned correctly. The surface where the DISPLACEMENT was assigned will be coloured:

IS_INTERFACE Assign the IS_INTERFACE flag, to indicate the FSI boundary: 2) IS_INTERFACE=1 on all the outer surfaces Fsi Structure->Nodal Values->IS_INTERFACE (on surface): (tick: is_fixed)‏ After assigning the IS_INTERFACE, click: Draw to check that the DISPL is assigned correctly. The surface where the IS_INTERFACE was assigned will be coloured:

Assign the Element Type (linear 4 node tetrahedra): 2) IS_INTERFACE=1 on all the outer surfaces Fsi Structure->Element Type->TotalLagrangian3D4N (on volume): After assigning the TotalLagrangian3D4N, click: Draw to check that the Element type is assigned Element Type

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Mesh the geometry (Mesh->Generate Mesh)‏ and press CALCULATE The structure part is ready for the FSI!

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques FLUID PREPARATION

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Open GiD Load the model: open the fluid part model fsi_model_fluid.gid the geometry will appear Load the problem type: Data->Problem Type: fsi_fluid Choose: Update to a new Problem Type

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Assign the boundary conditions: 1) Velocity at the inlet Fsi Fluid->Model Parts->Velocity Inlet (on surface): V_x=1.0; V_y=0.0, V_z=0.0 After assigning the velocity, click: Draw to check that the inlet velocity is assigned correctly. The surface where the velocity was assigned will be coloured:

Assign the boundary conditions: 2) No-slip conditions on all the surfaces except for the inlet surface (where inlet velicty was prescribed) Fsi Fluid->Model Parts->NoSlipCondition (on surface) After assigning the NoSlip, click: Draw to check that the NoSlip is assigned correctly. The surface witn NoSlip will be coloured:

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Assign the boundary conditions: 3) Zero pressure at the outflow Fsi Fluid->Nodal Values->Pressure=0 (tick: fixed)(on surface)‏ After assigning the Pressure, click: Draw to check that the Pressure is assigned correctly. The surface with Pressure will be coloured:

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Assign the boundary conditions: 4) IS_INTERFACE on the surfaces representing the Structure inside of Fluid Fsi Fluid->Nodal Values->IS_INTERFACE=0 (tick: fixed)(on surface)‏ After assigning the IS_INTERFACE, click: Draw to check that the IS_INTERFACE is assigned correctly.

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Assign the ELEMENT TYPE to the Fluid Volume 5) Choose Fluid3D elements Fsi Fluid->Elements -> Fluid3D (on VOLUME) After assigning the Fluid3D, click: Draw to check that the Element Type is assigned correctly

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Finally set the Problem Parameters Fsi Fluid->Problem Parameters Tick the first three boxes

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Finally set the Problem Parameters Fsi Fluid->Problem Parameters Time step to be used: Total time (not necessary)‏ Number of time steps

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Finally set the Problem Parameters Fsi Fluid->Problem Parameters Fractional Step Based solver will be used for the fluid Laplacian form:1 (contin. Laplacian) Laplacian form: 2 (discr. Laplacian DM-1G)

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Finally set the Problem Parameters Fsi Fluid->Problem Parameters LOAD NOW THE STRUCTURE FILE!!! browse: fsi_model_str.mdpa

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Model is ready -> Mesh the model 1) Mesh-> Unstructured->Assign Sizes on surfaces: 0.05 Choose the surfaces of the column 2) Mesh->Unstructured->Assign Sizes on volumes: 0.2 Choose the fluid volume 3) Mesh->Generate Mesh check that the mesh at the object is finer than the rest

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques Press: CALCULATE Pre-processing is finished

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques To run the example: 1) copy the fsi_model_str.mdpa from /fsi_model_str.gid/ folder into the /fsi_model_fluid.gid/ folder 2) inside the fsi_model_fluid.gid folder run: python run_example.py

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques In post-processing GiD mode, load the fsi_model_fluid.0.res.bin Post-processing To see the res.: View Results-> Contour Fill-> [Var of interest], e.g. [DISPLACEMENT]

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques If you would like to see the structural information, you need to change a few lines in the run_example.py file (just in the part that is marked here!!!) change: fluid_model_part to structure_model_part

GiD-Kratos Singapore Workshops Pre and Post Processing Techniques In post-processing mode, load the fsi_model_fluid.0.res.bin Post-processing To see the res.: View Results-> Contour Fill-> [Var of interest], e.g. [DISPLACEMENT]

Thanks… Kratos Web page: http://www.cimne.com/kratos/ Kratos Wiki http://kratos.cimne.upc.es/kratoswiki/index.php/Main_Page These Tutorials: http://kratos.cimne.upc.es/kratoswiki/index.php/Kratos_Tutorials