1! Computes the self-capacitance of a unit cube. Only 1/8 of the cube is 2! modeled. The cube is placed within a larger cube and at the external 3! walls infinite field approximation around origin is enforced. This 4! makes it possible not to extent the mesh into infinity. Note that 5! this approximation is valid only in 3D. Permittivity of vacuum is set 6! to one to allow easier interpretation of the computed capacitance. 7! 8! As the capacitance is 1.02213 the true capacitance is something like 9! 1.02213*8*eps. This is within 2% of the exact solution. 10! Increasing mesh density and taking the outer cube further apart. 11! will improve on the accuracy. 12! 13! P.R. / 18.2.2012 14 15Check Keywords Warn 16 17Header 18 Mesh DB "." "cubes" 19End 20 21Simulation 22 Coordinate System = Cartesian 3D 23 Simulation Type = Steady State 24 Steady State Max Iterations = 1 25! Output File = "elstatics.result" 26! Post File = "elstatics.ep" 27End 28 29Constants 30 Permittivity Of Vacuum = 1 31!8.8542e-12 32End 33 34Body 1 35 Equation = 1 36 Material = 1 37End 38 39Equation 1 40 Active Solvers(2) = 1 2 41 Calculate Electric Energy = True 42End 43 44Solver 1 45 Equation = Stat Elec Solver 46 Variable = Potential 47 Variable DOFs = 1 48 Procedure = "StatElecSolve" "StatElecSolver" 49 50 Calculate Electric Energy = True 51 Calculate Electric Field = False 52 Calculate Electric Flux = False 53 54 Calculate Capacitance Matrix = True 55 56 Linear System Solver = Iterative 57 Linear System Iterative Method = BiCGStab 58 Linear System Max Iterations = 500 59 Linear System Convergence Tolerance = 1.0e-10 60 Linear System Preconditioning = ILU1 61 Linear System ILUT Tolerance = 1.0e-03 62 Linear System Residual Output = 10 63 Nonlinear System Max Iterations = 1 64 Nonlinear System Convergence Tolerance = 1.0e-4 65 Nonlinear System Newton After Tolerance = 1.0e-3 66 Nonlinear System Newton After Iterations = 10 67 Nonlinear System Relaxation Factor = 1 68 Steady State Convergence Tolerance = 1.0e-4 69End 70 71Solver 2 72 Equation = Electric Force 73 Procedure = "ElectricForce" "StatElecForce" 74End 75 76Solver 3 77 Exec Solver = After All 78 Equation = SaveScalars 79 Procedure = "SaveData" "SaveScalars" 80! Filename = "scalars.dat" 81 Variable 1 = Potential 82 Operator 1 = max 83 Operator 2 = min 84End 85 86Material 1 87 Relative Permittivity = 1.0 88End 89 90Boundary Condition 1 91 Name = Bc_inner 92 Target Boundaries(2) = 2 6 93 94! The "Capacitance body" keyword automatically sets the potential. 95! Potential = 1.0 96 Calculate Electric Force = True 97 Capacitance Body = 1 98End 99 100Boundary Condition 2 101 Name = bc_Symmetry 102 Target Boundaries(3) = 1 4 5 103End 104 105Boundary Condition 3 106 Name = bc_outer 107 Target Boundaries(2) = 3 7 108 109! Two cocentric cubes would result to Dirichlet condition for the outer cube 110! This would result to significantly larger capacitance. 111! Potential = 0.0 112 113! This keyword enforces an approximation that assumes that the field decays as 1/r^2 to infinity 114 Electric Infinity BC = Logical True 115End 116 117Solver 1 :: Reference Norm = Real 0.482109 118RUN 119 120 121!End Of File 122 123