Surface Traction term for Navier Stokes
Hello,
I need to use a surface traction term, because I want to apply a pressure dirichlet boundary condition at the inlet for channel flow. In the SfePy term overview page, I can see the term dw_surface_ltr. In my weak form for the Navier Stokes equations, I will need two such terms. One for the stress tensor and one for the pressure. I got the pressure term using the dw_surface_ndot term. I do not understand how to represent the viscosity*vel_test_func.grad(velocity).n term.
Best regards, Nikhil
On 11/21/2016 04:04 PM, Nikhil Vaidya wrote:
Hello,
I need to use a surface traction term, because I want to apply a pressure dirichlet boundary condition at the inlet for channel flow. In the SfePy term overview page, I can see the term dw_surface_ltr. In my weak form for the Navier Stokes equations, I will need two such terms. One for the stress tensor and one for the pressure. I got the pressure term using the dw_surface_ndot term. I do not understand how to represent the viscosity*vel_test_func.grad(velocity).n term.
So viscosity * grad(velocity) is known, right? You can use dw_surface_ltr with the traction vector f = viscosity * grad(velocity) as the material parameter.
r.
Best regards, Nikhil
OK. It is still not completely clear to me. Should I define a user function and then pass it to the terms in the equation?
Best regards, Nikhil
On Monday, November 21, 2016 at 4:29:44 PM UTC+1, Robert Cimrman wrote:
Hello,
I need to use a surface traction term, because I want to apply a
On 11/21/2016 04:04 PM, Nikhil Vaidya wrote: pressure
dirichlet boundary condition at the inlet for channel flow. In the SfePy term overview page, I can see the term dw_surface_ltr. In my weak form for the Navier Stokes equations, I will need two such terms. One for the stress tensor and one for the pressure. I got the pressure term using the dw_surface_ndot term. I do not understand how to represent the viscosity*vel_test_func.grad(velocity).n term.
So viscosity * grad(velocity) is known, right? You can use dw_surface_ltr with the traction vector f = viscosity * grad(velocity) as the material parameter.
r.
Best regards, Nikhil
It depends if the given velocity is constant or not. If it is not constant, you need to define the material parameter using a function [1, 2].
r.
[1] http://sfepy.org/docdevel/users_guide.html#definingmaterialparameters [2] http://sfepy.org/docdevel/examples/linear_elasticity/linear_elastic_tractio...
On 11/21/2016 04:56 PM, Nikhil Vaidya wrote:
OK. It is still not completely clear to me. Should I define a user function and then pass it to the terms in the equation?
Best regards, Nikhil
On Monday, November 21, 2016 at 4:29:44 PM UTC+1, Robert Cimrman wrote:
Hello,
I need to use a surface traction term, because I want to apply a
On 11/21/2016 04:04 PM, Nikhil Vaidya wrote: pressure
dirichlet boundary condition at the inlet for channel flow. In the SfePy term overview page, I can see the term dw_surface_ltr. In my weak form for the Navier Stokes equations, I will need two such terms. One for the stress tensor and one for the pressure. I got the pressure term using the dw_surface_ndot term. I do not understand how to represent the viscosity*vel_test_func.grad(velocity).n term.
So viscosity * grad(velocity) is known, right? You can use dw_surface_ltr with the traction vector f = viscosity * grad(velocity) as the material parameter.
r.
Best regards, Nikhil
participants (2)

Nikhil Vaidya

Robert Cimrman