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4.14.3 General Specification of Fluid-FSI Materials
The material type for a fluid-FSI material is “fluid-FSI”. This type of material is used for fluid flow through a deforming mesh. The material is treated as a special case of fluid-solid mixture, with the solid material used to regularize the mesh deformation. The following parameters must be defined:
|<fluid>||Specification of fluid model|
|<solid>||Specification of elastic solid model for mesh deformation|
The <fluid> tag encloses a description of the fluid, as given in Section 4.14.1↑. The <solid> tag encloses a description of the solid, which should be modeled as an unconstrained elastic solid, as given in Section 4.1.3↑. The recommended choice is the unconstrained neo-Hookean solid defined in Section 220.127.116.11↑, with and set to a very small (but non-zero) value.
<material id="1" name="Fluid-FSI domain" type="fluid-FSI"> <fluid type="fluid"> <density>1000</density> <k>2.2e9</k> <viscous type="Newtonian fluid"> <mu>0.001</mu> <kappa>0</kappa> </viscous> </fluid> <solid type="neo-Hookean"> <density>0</density> <E>1e-9</E> <v>0</v> </solid> </material>
The value of <density> in the <solid> material is internally set to zero regardless of the user-defined value, since the deforming mesh should not be subjected to inertial forces.