| 1 | /* Copyright (c) 2008, 2010 The University of Notre Dame. All Rights Reserved. | 
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| 9 | *    notice, this list of conditions and the following disclaimer. | 
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| 16 | * This software is provided "AS IS," without a warranty of any | 
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| 30 | * | 
| 31 | * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your | 
| 32 | * research, please cite the appropriate papers when you publish your | 
| 33 | * work.  Good starting points are: | 
| 34 | * | 
| 35 | * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005). | 
| 36 | * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006). | 
| 37 | * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008). | 
| 38 | * [4] Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010). | 
| 39 | * [4] , Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011). * | 
| 40 | * | 
| 41 | *  Triangle.cpp | 
| 42 | * | 
| 43 | *  Purpose: Provide basic triangle object for OpenMD | 
| 44 | * | 
| 45 | *  Created by Charles F. Vardeman II on 29 July 2008. | 
| 46 | *  @author  Charles F. Vardeman II | 
| 47 | *  @version $Id$ | 
| 48 | * | 
| 49 | */ | 
| 50 |  | 
| 51 | #include "math/Triangle.hpp" | 
| 52 |  | 
| 53 | using namespace OpenMD; | 
| 54 |  | 
| 55 |  | 
| 56 | Triangle::Triangle() :  normal_(V3Zero), centroid_(V3Zero), area_(0.0), | 
| 57 | mass_(0.0), facetVelocity_(V3Zero), | 
| 58 | a_(V3Zero), b_(V3Zero), c_(V3Zero), | 
| 59 | HaveArea_(false), HaveNormal_(false), | 
| 60 | HaveUnitNormal_(false), HaveCentroid_(false) {} | 
| 61 |  | 
| 62 | void Triangle::addVertices(Vector3d P1, Vector3d P2, Vector3d P3){ | 
| 63 | vertices_[0] = P1; | 
| 64 | vertices_[1] = P2; | 
| 65 | vertices_[2] = P3; | 
| 66 |  | 
| 67 | // Compute some quantites like a,b,c | 
| 68 | a_ = P1-P2; | 
| 69 | b_ = P1-P3; | 
| 70 | c_ = P2-P3; | 
| 71 | } | 
| 72 |  | 
| 73 |  | 
| 74 | RealType Triangle::computeArea(){ | 
| 75 | HaveArea_ = true; | 
| 76 | area_ = getNormal().length() * 0.5; | 
| 77 | return area_; | 
| 78 | } | 
| 79 | // This should return the normal for our calculations. | 
| 80 | Vector3d Triangle::computeNormal(){ | 
| 81 | HaveNormal_ = true; | 
| 82 | normal_ = cross(a_,b_); | 
| 83 | return normal_; | 
| 84 | } | 
| 85 | // This should return the normal for our calculations. | 
| 86 | Vector3d Triangle::computeUnitNormal(){ | 
| 87 | HaveUnitNormal_ = true; | 
| 88 | unitnormal_ = cross(a_,b_); | 
| 89 | unitnormal_.normalize(); | 
| 90 | return unitnormal_; | 
| 91 | } | 
| 92 |  | 
| 93 | Vector3d Triangle::computeCentroid(){ | 
| 94 | HaveCentroid_ = true; | 
| 95 | centroid_ = (vertices_[0] + vertices_[1] + vertices_[2])/RealType(3.0); | 
| 96 | return centroid_; | 
| 97 | } | 
| 98 |  | 
| 99 |  | 
| 100 | Mat3x3d Triangle::computeHydrodynamicTensor(RealType viscosity) { | 
| 101 |  | 
| 102 | Vector3d u0 = -a_; | 
| 103 | Vector3d v0 = centroid_ - vertices_[0]; | 
| 104 | RealType s0 = 0.5*cross(u0,v0).length(); | 
| 105 |  | 
| 106 | Vector3d u1 = -c_; | 
| 107 | Vector3d v1 = centroid_ - vertices_[1]; | 
| 108 | RealType s1 = 0.5*cross(u1,v1).length(); | 
| 109 |  | 
| 110 | Vector3d u2 = b_; | 
| 111 | Vector3d v2 = centroid_ - vertices_[2]; | 
| 112 | RealType s2 = 0.5*cross(u2,v2).length(); | 
| 113 |  | 
| 114 | Mat3x3d H; | 
| 115 | H = hydro_tensor(centroid_,centroid_,vertices_[1],vertices_[0],s0,viscosity)+ | 
| 116 | hydro_tensor(centroid_,centroid_,vertices_[1],vertices_[2],s1,viscosity)+ | 
| 117 | hydro_tensor(centroid_,centroid_,vertices_[2],vertices_[0],s2,viscosity); | 
| 118 |  | 
| 119 | return H.inverse(); | 
| 120 | } | 
| 121 |  | 
| 122 | Mat3x3d Triangle::hydro_tensor( | 
| 123 | const Vector3d& ri, | 
| 124 | const Vector3d& rj0, | 
| 125 | const Vector3d& rj1, | 
| 126 | const Vector3d& rj2, | 
| 127 | RealType s, RealType viscosity){ | 
| 128 |  | 
| 129 | Vector3d v2 = (rj0 + rj1 + rj2) / RealType(3.0);  // sub-centroid | 
| 130 | Vector3d dr = ri - v2;                // real centroid to sub-centroid | 
| 131 | RealType l2 = RealType(1.0)/dr.lengthSquare(); | 
| 132 |  | 
| 133 | Mat3x3d G; | 
| 134 | G = (SquareMatrix3<RealType>::identity() + outProduct(dr,dr)*l2)*RealType(sqrt(l2)); | 
| 135 |  | 
| 136 | G *= 0.125/3.14159285358979; | 
| 137 | G *= s/viscosity; | 
| 138 | return G; | 
| 139 | } |