actual fluid pressure

Module: solute

Category: bc

Type string: "actual fluid pressure"

Parameters

Name	Description	Default	Units
pressure	fluid pressure	0	[P]
shell_bottom	shell_bottom	false	[]

Description

In a multiphasic mixture the nodal degree of freedom for fluid pressure represents the effective fluid pressure \(\tilde{p}\), which is related to the actual fluid pressure \(p\). One may assign the value of \(p\) directly on a boundary, by using the actual fluid pressure boundary condition.

<bc surface="FluidPressure1" type="actual fluid pressure">
  <pressure>0</pressure>
  <shell_bottom>0</shell_bottom>
</bc>

This boundary condition evaluates \(p\) from nodal values of \(\tilde{p}\) on the surface, and using the average values of \(\Phi\) and \(c^{\alpha}\) at the integration points of the underlying element. This surface load is particularly useful when the effective solute concentrations \(\tilde{c}^{\alpha}\) are not prescribed as boundary conditions on that surface, but evolve with the analysis solution.

The shell_bottom boolean flag (0=false, 1=true) should be set to true when prescribing this pressure on the bottom of a multiphasic shell domain.Prescribe the actual fluid pressure in a multiphasic mixture.