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-   -   Need help for a simple example with icoFOAM (http://www.cfd-online.com/Forums/openfoam-solving/59757-need-help-simple-example-icofoam.html)

gruber2 April 3, 2007 04:20

Hello, i need help for a si
 
Hello,

i need help for a simple example with OpenFOAM.

Given:
Inlet: Zylinder with Diameter 125mm (200mm long)
A Inlet = D Inlet≤*Pi/4 = 0,125≤ *3.14 / 4 = 0.0123m≤
Vpoint=2400l/min=0.04m≥/s
Fluid Oil: rho=0.9kg/dm≥=900kg/m≥
eta= 1 Pa s = 1 kg / (m s)
Outlet: Zylinder with Diameter 200mm (200mm long)
A Outlet = D Outlet≤*Pi/4 = 0,2≤ *3.14 / 4 = 0.0314m≤

Necessary values for the calculation with OpenFOAM:
v Inlet=Vpoint / A Inlet= 0.04 / 0.0123 = 3.25 m/s -> inscribed in $FOAM_RUN/tutorials/icoFoam/tube/0/U
p Inlet= rho * v Inlet≤ / 2= 900 * 3,25≤ / 2 = 4753.125 Pa -> inscribed in $FOAM_RUN/tutorials/icoFoam/tube/0/p
Re = D Inlet * v Inlet * rho / eta = 0,125 * 3.25 * 900 / 1 = 365,625 <re> laminar Flow -> Solver: icoFOAM
ny = D Inlet * v Inlet / Re = 0,125 * 3.25 / 365,625 = 0.001 m≤ / s -> inscribed in $FOAM_RUN/tutorials/icoFoam/tube/constant/transportProperties
endTime 0.5; deltaT 0.005; writeInterval 20 -> inscribed in $FOAM_RUN/tutorials/icoFoam/tube/system/controlDict
div(phi,U) Gauss <>; changed in -> div(phi,U) Gauss linear; in $FOAM_RUN/tutorials/icoFoam/tube/system/fvSchemes:

Requested values:
v Outlet, p Outlet
Calculated values for Control:
v Outlet=v Inlet * A Inlet / A Outlet = 3.25 * 0.0123 / 0.0314 = 1,27 m/s
p Outlet= rho * v Outlet≤ / 2= 900 * 1,27≤ / 2 = 725,805 Pa

My problem is:
The fact that the speed (picture tube-u0) and Pressure (picture tube-p0) is indicated only in the Inlet at the start time and not for all other times, it is also not to be recognised with the filter glyth.










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