time varying velocity outlet boundary condition
Dear all,
I am simulating flow inside the pipe considering time varying decrease of outlet velocity. for decreasing outlet velocity by time I used the groovy BC boundary condition for velocity as follows: velocity:::: boundaryField { inlet { type zeroGradient; } outlet { type groovyBC; variables "U0=0.13;T1=3754;Uout=U0*(1-pow((time()/T1),3));"; valueExpression "(time()<T1) ? vector(Uout,0,0):vector (0,0,0)"; } axi_symm-f { type wedge; } axi_symm-r { type wedge; } wall { type fixedValue; value uniform (0 0 0); } defaultFaces { type empty; } } pressure::::: boundaryField { inlet { type fixedValue; value uniform 8376; } outlet { type zeroGradient; } axi_symm-f { type wedge; } axi_symm-r { type wedge; } wall { type zeroGradient; } defaultFaces { type empty; } } the problem is that after running the case on the terminal page the following message is presented: --> FOAM Warning : From function groovyBCFvPatchField<Type>::groovyBCFvPatchField(c onst fvPatch& p,const DimensionedField<Type, volMesh>& iF,const dictionary& dict) in file groovyBCFvPatchField.C at line 131 No value defined for U on outlet therefore using 30{(0 0 0)} I think it means that the groovy BC is not defined for outlet condition. But as I have to reduce the outlet velocity by time could any one help me for finding a proper boundary condition:confused::confused::confused::confused:. Many thanks for the help, Simin |
any idea????
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Hi,
From the error message, "No value defined for U on outlet therefore using 30{(0 0 0)}". So, you haven't defined any value,i.e. initial, at the boundary and it's taking some default value. What you can do is that, outlet { type groovyBC; variables "U0=0.13;T1=3754;Uout=U0*(1-pow((time()/T1),3));"; valueExpression "(time()<T1) ? vector(Uout,0,0):vector (0,0,0)"; value $internalField; Or uniform (0 0 0) if zero. } |
Hi Ahmmed,
Many thanks for your help :) |
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