time_integration_rule.hpp

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// Copyright (c) Lawrence Livermore National Security, LLC and
// other Smith Project Developers. See the top-level LICENSE file for
// details.
//
// SPDX-License-Identifier: (BSD-3-Clause)
 
#pragma once
 
#include "smith/physics/common.hpp"
 
namespace smith {
 
struct BackwardEulerFirstOrderTimeIntegrationRule {
  BackwardEulerFirstOrderTimeIntegrationRule() {}
 
  template <typename T1, typename T2>
  SMITH_HOST_DEVICE auto value(const TimeInfo& /*t*/, const T1& field_new, const T2& /*field_old*/) const
  {
    return field_new;
  }
 
  template <typename T1, typename T2>
  SMITH_HOST_DEVICE auto dot(const TimeInfo& t, const T1& field_new, const T2& field_old) const
  {
    return (1.0 / t.dt()) * (field_new - field_old);
  }
};
 
using QuasiStaticFirstOrderTimeIntegrationRule = BackwardEulerFirstOrderTimeIntegrationRule;
 
struct ImplicitNewmarkSecondOrderTimeIntegrationRule {
  ImplicitNewmarkSecondOrderTimeIntegrationRule() {}
 
  template <typename T1, typename T2, typename T3, typename T4>
  SMITH_HOST_DEVICE auto value([[maybe_unused]] const TimeInfo& t, [[maybe_unused]] const T1& field_new,
                               [[maybe_unused]] const T2& field_old, [[maybe_unused]] const T3& velo_old,
                               [[maybe_unused]] const T4& accel_old) const
  {
    return field_new;
  }
 
  template <typename T1, typename T2, typename T3, typename T4>
  SMITH_HOST_DEVICE auto dot([[maybe_unused]] const TimeInfo& t, [[maybe_unused]] const T1& field_new,
                             [[maybe_unused]] const T2& field_old, [[maybe_unused]] const T3& velo_old,
                             [[maybe_unused]] const T4& accel_old) const
  {
    return (2.0 / t.dt()) * (field_new - field_old) - velo_old;
  }
 
  template <typename T1, typename T2, typename T3, typename T4>
  SMITH_HOST_DEVICE auto ddot([[maybe_unused]] const TimeInfo& t, [[maybe_unused]] const T1& field_new,
                              [[maybe_unused]] const T2& field_old, [[maybe_unused]] const T3& velo_old,
                              [[maybe_unused]] const T4& accel_old) const
  {
    auto dt = t.dt();
    return (4.0 / (dt * dt)) * (field_new - field_old) - (4.0 / dt) * velo_old - accel_old;
  }
};
 
}  // namespace smith