boundary conditions and artificial viscosity
Hey everyone!
I am using the Jameson dissipation terms in my solver, and I was wondering what to do at the boundaries. I read in some papers that the dissipation was sometime set to zero at the wall. Why is that so? why shouldn't I compute the value of the dissipation term at the wall assuming that u = 0 (viscous)? I guess that at the inlet/outlet, I can simply compute the dissipation terms from the boundary values. Any suggestions?? Thanks! Joachim 
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artificial dissipation is just a trick to stabilize the numerical solution across zones where strong gradients are present and can generate oscillations, so it should be added only locally 
Thanks for your answer!
However, I am using a central scheme for my convective terms (+RK order 4), so that I need fourth order artificial viscosity to remove any odd/even decoupling. 
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but artificial dissipation is modulated by the local gradient intensity... do you have strong gradients as BC.s? 
well, I am computing the flow over a laminar flat plate right now, so I have gradients at the wall...

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This is not clear ... when you solve laminar flow, there is no unresolvable gradient in such case, therefore the artificial dissipation does not make sense... 
I have the values at time step n, and I explicitly compute the fluxes to get the state vector at time step n+1. However, I don't know if I should include the artificial viscosity at the wall or not...

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