dbpp_TimeStepCondition.hpp

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#pragma once
 
// C++20 includes
#include <ranges>
#include <optional>
// STL include
#include <algorithm>
// numeric include
#include <valarray>
//
#include "include/Sfx_UniversalConstants.h "//gravity
#include "include/Sfx_DefineTypes.h"  //float64
// VS19 include
#include "../../Nov_VS2019/dbpp_ListSectionsFlow.h"
 
#undef min
 
namespace dbpp 
{
  std::optional<float64> TimeStepCondition( std::ranges::view auto aU1, 
    std::ranges::view auto aU2, bool isSectionUnitWidth=true)
  {
    namespace rng = std::ranges;
    
    assert(rng::size(aU1) == rng::size(aU2));
 
    // NOTE 'dx' is hard coded
//    DamBreakData w_dbData(Simulation::instance()->getDBdata());
    //w_dbData.initMcNeil1D();
 
 //   const auto B = w_dbData.getWidth();
 //   const auto dx = w_dbData.dX();
 
 
    // only suporting section of unit width in this release
    if (!isSectionUnitWidth) return std::nullopt;
 
    // IMPORTANT
    // first node is tie not considered j=1
    //  Calcul des valeurs des variables d'état
    //  for (auto j = 1; j < aU1.size(); j++)
    //  {
    // IMPORTANT-
    //  this algorithm assume far left node is tied (physical boundary condition)
    std::valarray<rng::range_value_t<decltype(aU1)>> w_U1(aU1.data(),aU1.size());
    std::valarray<rng::range_value_t<decltype(aU1)>> w_U2(aU2.data(),aU2.size());
 
    // FIX THAT!!!
    // debug purpose
    //const auto B = 1.; w_dbData.getWidth();
    constexpr auto dx = 0.01; //w_dbData.dX();
   // Sfx::DamBreakData aDamBreakData{ Sfx::SimulationMgr::getSingleton().getDBdataType() };
    // Analyse des conditions de stabilité numérique
    auto V = w_U2 / w_U1;
    auto c = std::sqrt(Sfx::cGravity<float64>*w_U1); // / HydroUtils::T(B));    // T à calculer
    auto dtc = dx / (std::abs(V) + c);
    // return min value
    return dtc.min();
  }
}// End of namespace