00001 /*---------------------------------------------------------------------------*\ 00002 ========= | 00003 \\ / F ield | OpenFOAM: The Open Source CFD Toolbox 00004 \\ / O peration | 00005 \\ / A nd | Copyright (C) 1991-2010 OpenCFD Ltd. 00006 \\/ M anipulation | 00007 ------------------------------------------------------------------------------- 00008 License 00009 This file is part of OpenFOAM. 00010 00011 OpenFOAM is free software: you can redistribute it and/or modify it 00012 under the terms of the GNU General Public License as published by 00013 the Free Software Foundation, either version 3 of the License, or 00014 (at your option) any later version. 00015 00016 OpenFOAM is distributed in the hope that it will be useful, but WITHOUT 00017 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00018 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 00019 for more details. 00020 00021 You should have received a copy of the GNU General Public License 00022 along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>. 00023 00024 Class 00025 Foam::filteredLinearLimiter 00026 00027 Description 00028 Class to generate weighting factors for the filteredLinear 00029 differencing scheme. 00030 00031 The aim is to remove high-frequency modes with "staggering" 00032 characteristics by comparing the face gradient relative to the 00033 background distribution represented by the neighbouring cell gradients 00034 with those gradients and introduce small amounts of upwind in order to 00035 damp these modes. 00036 00037 Used in conjunction with the template class LimitedScheme. 00038 00039 SourceFiles 00040 filteredLinear.C 00041 00042 \*---------------------------------------------------------------------------*/ 00043 00044 #ifndef filteredLinear_H 00045 #define filteredLinear_H 00046 00047 #include <OpenFOAM/vector.H> 00048 00049 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 00050 00051 namespace Foam 00052 { 00053 00054 /*---------------------------------------------------------------------------*\ 00055 Class filteredLinearWeight Declaration 00056 \*---------------------------------------------------------------------------*/ 00057 00058 template<class LimiterFunc> 00059 class filteredLinearLimiter 00060 : 00061 public LimiterFunc 00062 { 00063 00064 public: 00065 00066 filteredLinearLimiter(Istream&) 00067 {} 00068 00069 scalar limiter 00070 ( 00071 const scalar cdWeight, 00072 const scalar faceFlux, 00073 const typename LimiterFunc::phiType& phiP, 00074 const typename LimiterFunc::phiType& phiN, 00075 const typename LimiterFunc::gradPhiType& gradcP, 00076 const typename LimiterFunc::gradPhiType& gradcN, 00077 const vector& d 00078 ) const 00079 { 00080 scalar df = phiN - phiP; 00081 00082 scalar dcP = d & gradcP; 00083 scalar dcN = d & gradcN; 00084 00085 scalar limiter = 00086 2 00087 - 0.5*min(mag(df - dcP), mag(df - dcN)) 00088 /(max(mag(dcP), mag(dcN)) + SMALL); 00089 00090 // Limit the limiter between linear and 20% upwind 00091 return max(min(limiter, 1), 0.8); 00092 } 00093 }; 00094 00095 00096 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 00097 00098 } // End namespace Foam 00099 00100 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 00101 00102 #endif 00103 00104 // ************************ vim: set sw=4 sts=4 et: ************************ //
