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boiling, drag_force

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Old   December 6, 2007, 05:18
Default boiling, drag_force
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SMF_MS
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Hi Folks,

i am using the boiling tutorial. In DEFINE_EXCHANGE_PROPERTY the drag coefficient is calculated. Instead of this coefficient the drag force/urel is returned. I think that is wrong.

in literature: (Drag Force = 0.125 * drag_coeff * C_R(c,pt[second_column_phase_index]) * Ai * urel * urel)

Could anybody help, maybe i have got an error in reasoning.

Thank you.

/* Calculation of the drag coefficient */

drag_vis = 24.*(1.+0.1*pow(reb,0.75))/MAX(reb,1e-10) / pow(MAX(1-vof_vapor,0.5),2.);

Rol = C_R(c,pt[second_column_phase_index]);

Rov = C_R(c,pt[first_column_phase_index]);

coeff = (Rol-Rov)*gravity/sigma ;

drag_coeff = 0.666*dbub*pow(coeff,0.5) / pow(MAX(1-vof_vapor,0.5),1.0);

if (drag_vis > drag_coeff) drag_coeff = drag_vis;

drag_force = 0.125 * drag_coeff * C_R(c,pt[second_column_phase_index])

* Ai * urel ;

C_UDMI(c,mixture_thread,3) = drag_force * urel * urel;

C_UDMI(c,mixture_thread,4) =

0.45 * C_UDMI(c,mixture_thread,3) * drag_coeff * urel / dbub;

return drag_force;

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