2f62a7e658
git-svn-id: http://svn.sintef.no/trondheim/IFEM/trunk@2927 e10b68d5-8a6e-419e-a041-bce267b0401d
101 lines
2.3 KiB
C
101 lines
2.3 KiB
C
//==============================================================================
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//!
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//! \file SAWallLaw.C
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//!
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//! \date Jun 19 2013
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//!
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//! \author Runar Holdahl / SINTEF
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//!
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//! \brief Implementation of Spalding parametrization of a turbulent
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//! boundary layer. Computes the mean velocity uplus parallel
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//! to a solid wall given the distance y and the tangential
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//! velocity component ut.
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//!
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//==============================================================================
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#include "SAWallLaw.h"
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SAWallLaw::f_SA_wall_law::f_SA_wall_law() : B(5.03339087905055799), a1(8.148221580024245),
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a2(-6.9287093849022945), b1(7.4600876082527945), b2(7.468145790401841),
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c1(2.5496773539754747), c2(1.3301651588535228), c3(3.599459109332379),
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c4(3.6397531868684494)
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{}
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bool SAWallLaw::computeYplus(double y, double nu, double utan, double& yplus) const
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{
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// Initial guess
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yplus = y;
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// yplus is zero for zero tangential velocity
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if (utan < 1.0e-12)
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return true;
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// Residual
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double uplus = y*utan/(nu*yplus);
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double r = uplus - SA.up(yplus);
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int it = 0;
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double drdyplus;
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while ((fabs(r) > rtol) && (it < maxit)) {
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drdyplus = -y*utan/(nu*yplus*yplus) - SA.dupdyp(yplus);
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yplus -= r/drdyplus;
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yplus = fabs(yplus);
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uplus = y*utan/(nu*yplus);
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r = uplus - SA.up(yplus);
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it++;
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}
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return (it < maxit);
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}
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bool SAWallLaw::computeUstar(double y, double nu, double utan, double& ustar) const
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{
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double yplus;
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if (!this->computeYplus(y,nu,utan,yplus))
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return false;
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double uplus = SA.up(yplus);
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ustar = utan/uplus;
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return true;
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}
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bool SAWallLaw::computeTauB(double y, double nu, double utan, double& tauB) const
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{
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// Constant
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const double CbI = 4.0;
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// Initial guess
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tauB = CbI*nu/y;
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if (utan < 1.0e-12)
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return true;
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double yplus;
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if (!this->computeYplus(y,nu,utan,yplus))
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return false;
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double uplus = SA.up(yplus);
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double ustar = utan/uplus;
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tauB = ustar*ustar/utan;
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return true;
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}
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bool SAWallLaw::computeNu(double y, double nu, double utan, double& nuwall) const
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{
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double yplus;
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if (!this->computeYplus(y,nu,utan,yplus))
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return false;
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//! Wall BC for Spalart-Allmaras
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double uplus = SA.up(yplus);
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double ustar = utan/uplus;;
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nuwall = K*ustar*y;
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return true;
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}
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