# Linear Velocity Inlet Boundary Condition in Openfoam

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 February 26, 2016, 18:11 Linear Velocity Inlet Boundary Condition in Openfoam #1 New Member   Shahil Join Date: Jan 2016 Posts: 5 Rep Power: 7 I am analyzing turbulent flow over a flat plate and I am trying to specifying inlet velocity as U = Sx*y; where y is the wall-normal co-ordinate and Sx is shear rate, the value I calculated as 11800. In boundary condition folder for U, I tried specifying linear inlet velocity as follows: inlet { type uniformValue; uniformValue polynomial ( ( ( 11800 0 0 ) ( 1 0 0 ) ) ); } The solver is showing following error. file: /air/U.boundaryField.inlet from line 31 to line 32. From function fvPatchField::New(const fvPatch&, const DimensionedField&, const dictionary&) in file /home/lab/OpenFOAM/OpenFOAM-2.3.x/src/finiteVolume/lnInclude/fvPatchFieldNew.C at line 143. FOAM exiting Please give your suggestions. Please help.

 February 27, 2016, 03:00 #2 Senior Member   Join Date: Sep 2013 Posts: 269 Rep Power: 16 polynomial works in the following way: Code: ```uniformValue polynomial // y = 0.1 + 1.3x^2 + 2.7x^3 ( (0.1 0) (1.3 2.0) (2.7 3.0) );``` for a vector it is therefore Code: ```uniformValue polynomial // y = 0.1 + 1.3x^2 + 2.7x^3 ( (0.1 (0 0 0)) (1.3 (0 0 2.0)) (2.7 (0 0 3.0)) );``` this is a time varying boundary condition that assignes a uniform value that is interpolated using the given polynomial. I suppose you want a boundary condition that gives you such a velocity profile .../ ../ ./ / You could check if sawkForFoam offers this or program your own. For this purpose you could take a look at the parabolic inlet boundary conditions.

 Tags boundary condition, pre-processing, u folder, velocity inlet