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chore: Refactor CFL condition calculation in Simulation constructor

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This commit is contained in:
Max Lübke 2024-05-08 12:52:18 +02:00
parent 449647010a
commit a197916fc6
1 changed files with 33 additions and 19 deletions
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52
include/tug/Simulation.hpp
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@ -181,28 +181,10 @@ public:
if (timestep <= 0) { if (timestep <= 0) {
throw_invalid_argument("Timestep has to be greater than zero."); throw_invalid_argument("Timestep has to be greater than zero.");
} }
const T cfl = get_cfl_ftcs(timestep);
if constexpr (approach == FTCS_APPROACH || if constexpr (approach == FTCS_APPROACH ||
approach == CRANK_NICOLSON_APPROACH) { approach == CRANK_NICOLSON_APPROACH) {
T cfl;
if (grid.getDim() == 1) {
const T deltaSquare = grid.getDelta();
const T maxAlpha = grid.getAlpha().maxCoeff();
// Courant-Friedrichs-Lewy condition
cfl = deltaSquare / (4 * maxAlpha);
} else if (grid.getDim() == 2) {
const T deltaColSquare = grid.getDeltaCol() * grid.getDeltaCol();
// will be 0 if 1D, else ...
const T deltaRowSquare = grid.getDeltaRow() * grid.getDeltaRow();
const T minDeltaSquare = std::min(deltaColSquare, deltaRowSquare);
const T maxAlpha =
std::max(grid.getAlphaX().maxCoeff(), grid.getAlphaY().maxCoeff());
cfl = minDeltaSquare / (4 * maxAlpha);
}
const std::string dim = std::to_string(grid.getDim()) + "D"; const std::string dim = std::to_string(grid.getDim()) + "D";
const std::string &approachPrefix = this->approach_names[approach]; const std::string &approachPrefix = this->approach_names[approach];
@ -233,6 +215,14 @@ public:
<< std::endl; << std::endl;
} }
} else { } else {
std::cout << "Info :: CFL condition for FTCS would require a maximum "
"timestep of "
<< cfl << " [s].\n"
<< "Info :: Used timestep is " << timestep << " [s].\n"
<< "Info :: This is " << timestep / cfl
<< " times the CFL condition."
<< "\n\n";
this->timestep = timestep; this->timestep = timestep;
} }
} }
@ -498,6 +488,30 @@ private:
Grid<T> &grid; Grid<T> &grid;
Boundary<T> &bc; Boundary<T> &bc;
T get_cfl_ftcs(T timestep) {
if (grid.getDim() == 1) {
const T deltaSquare = grid.getDelta();
const T maxAlpha = grid.getAlpha().maxCoeff();
// Courant-Friedrichs-Lewy condition
return deltaSquare / (4 * maxAlpha);
} else if (grid.getDim() == 2) {
const T deltaColSquare = grid.getDeltaCol() * grid.getDeltaCol();
// will be 0 if 1D, else ...
const T deltaRowSquare = grid.getDeltaRow() * grid.getDeltaRow();
const T minDeltaSquare = std::min(deltaColSquare, deltaRowSquare);
const T maxAlpha =
std::max(grid.getAlphaX().maxCoeff(), grid.getAlphaY().maxCoeff());
return minDeltaSquare / (4 * maxAlpha);
}
// should not happen ...
return -1;
}
const std::vector<std::string> approach_names = {"FTCS", "BTCS", "CRNI"}; const std::vector<std::string> approach_names = {"FTCS", "BTCS", "CRNI"};
}; };
} // namespace tug } // namespace tug