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-   -   can phoenics simulate lake flow under wind drag (http://www.cfd-online.com/Forums/phoenics/51781-can-phoenics-simulate-lake-flow-under-wind-drag.html)

wady August 3, 2004 05:08

can phoenics simulate lake flow under wind drag
 
hello,everyone:

Now i am dealing a problem about lake simulation. I want to add the wind effect to my math model. but how to consider the wind's effect on water in phoenics? Add some source or adapt the model of the two-phase flow?

thank you!

PHOENICS User August 5, 2004 10:23

Re: can phoenics simulate lake flow under wind dra
 
You can simply employ a rigid-lid assumption for the lake surface, and then introduce a source of momentum into the cells adjacent to the surface of the lake for the water surface velocities that experience wind-induced shear.

The source term in Newtons for each surface-velocity momentum equation can be of the form:

S = Area * F * Density,air * abs(Vrel) *(Vwind - Vwat)

where Area=surface area of the lake-surface cell, F=friction coefficient of the order of 1E-3, and Vrel is the relative absolute velocity equal to (Vwind-Vwater). Here, Vwat is the local velocity of the water as solved in the PHOENICS momentum equation.


wady August 9, 2004 04:37

Re: can phoenics simulate lake flow under wind dra
 
Thank you for your help!But how can i implement in phoenics?through ground or plant?i am more familar with the VR, can it be settled in VR?


PHOENICS User August 17, 2004 06:37

Re: can phoenics simulate lake flow under wind dra
 
For the case of a wind velocity aligned with one of the coordinate axes, the source can be introduced without recourse to INFORM, PLANT or GROUND if you use a user-defined object at the surface of the water, and then introduce the required quadratic source by means of AREA-type PATCH for the momentum equation in that coordinate direction. The COefficient must be assigned a negative value (the -sign serves as a flag for PHOENICS to identify that a quadratic source is requested), as follows:

CO = - rho,air*friction factor

and the VAL should be set equal to Vwind. The source term introduced is:

S = Area*ABS(CO)*ABS[Vwind -Vp]*(Vwind-Vp)

Note that the negative coefficient option only applies to a constant coefficient. It does not apply to GROUND-set coefficients.


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