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How to add X and Y forces at a point

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Old   February 9, 2015, 13:29
Default How to add X and Y forces at a point
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Hello,

I am trying simulate a plasma actuator on an airfoil.

To do so, I need to add a force in the x and y directions to specific points in the domain. I am currently trying to add the force in "numerics_direct_mean.cpp". When the code passes through a certain array of points, I add the following to each location:

val_residual[1] = Volume * fx;
val_residual[2] = Volume * fy;

However, I am not getting the results I expect.

Do val_residual [1] and [2] add forces to the x and y directions, respectively? Or is there another way to add the forces?

The simulations use Euler equations with a NACA0012 airfoil at a 10 degree angle of attack.

Thank you
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Old   February 10, 2015, 22:06
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hlk
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Heather Kline
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Quote:
Originally Posted by cgusty01 View Post
Hello,

I am trying simulate a plasma actuator on an airfoil.

To do so, I need to add a force in the x and y directions to specific points in the domain. I am currently trying to add the force in "numerics_direct_mean.cpp". When the code passes through a certain array of points, I add the following to each location:

val_residual[1] = Volume * fx;
val_residual[2] = Volume * fy;

However, I am not getting the results I expect.

Do val_residual [1] and [2] add forces to the x and y directions, respectively? Or is there another way to add the forces?

The simulations use Euler equations with a NACA0012 airfoil at a 10 degree angle of attack.

Thank you
Review the discretization of the Euler equations to make sure that setting the residual of the momentum flux to force*volume is actually what you want to do here. A good source is Numerical Computation of Internal & External Flows by Hirsch. Check that the residual is being updated in the linear system through a LinSysRes method, and review the other boundary conditions to see how these things are handled elsewhere in the code - there are often additional steps beyond setting a residual. It may be better to created a new boundary condition for what you are trying to do.
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Old   February 12, 2015, 15:16
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Thank you for your answer.

I am trying to add a volumetric force, not a boundary force. I do call LinSysRes. My question is if elements 1 and 2 in val_residual[] correspond to the x- and y- momentum equations.
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Old   February 18, 2015, 05:18
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Matt Wright
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Hi,

Have you managed to get much further with this? I'm trying to do a similar thing for my 3rd year project without success. Would it be possible if you could post your code up?

Many Thanks
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Old   February 18, 2015, 14:17
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Hi all,

My recommendation is to take a look at
void CEulerSolver::Source_Residual(CGeometry *geometry, CSolver **solver_container, CNumerics *numerics, CNumerics *second_numerics, CConfig *config, unsigned short iMesh)

there are several examples there and, depending of the complexity of the source term, we directly compute the residual at that subroutine or we use the numerics structure.

In particular the free surface or time_spectral examples are quite clear.

Thanks for using SU2,

Best

Francisco Palacios
SU2 lead developer
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