ARE zeroGradient in groovyBC and internalFiald different in result?
when I set BC for U to zeroGradient or:
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right but when I set it to: Code:
right Code:
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thank you dear Bernard.
I grasped the total idea.but implicit and explicit you mentioned you mean same as those are used in equations?could you explain a little more about the difference? does in the second case the solver takes the internalField(U) and put it exactly on the boundary but in the first(zeroGradient) it uses next time step value of internalField(U) and put it to the boundary? |
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- leave your fingers of it (99.5% of all users don't need internalField) - read a textbook (like Versteeg "An introduction to compuational fluid dynamics") where the discretization of equations (and boundary conditions!) is explained. The nomenclature may be different but it will be clear to you what implicit/"in the matrix" means |
no I'm among thos .5% ! need to use internalField.
is there a way to use gradientExpression so that a minus to be multiply to internal value? ( i need it for velocity) how can use gradientExpression except of velocity(0,0,0)?! |
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yes i knew that but didn't expect that much difference in stability.that problem is resolved now.
I mean how can implement an statement like vector(-internalField(U),0,0) (in the condition that flow is outward in a inlet patch by gradientExpression because most usage of it is with zero |
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