ESPResSo
Extensible Simulation Package for Research on Soft Matter Systems
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LBFluidPressureTensor.hpp
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1/*
2 * Copyright (C) 2010-2022 The ESPResSo project
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4 * This file is part of ESPResSo.
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19#ifndef OBSERVABLES_LB_FLUID_STRESS_HPP
20#define OBSERVABLES_LB_FLUID_STRESS_HPP
21
22#include "Observable.hpp"
23#include "system/System.hpp"
24
25#include <utils/math/sqr.hpp>
27
28#include <boost/mpi/collectives/reduce.hpp>
29
30#include <cstddef>
31#include <functional>
32#include <vector>
33
34namespace Observables {
36public:
37 std::vector<std::size_t> shape() const override { return {3, 3}; }
38 std::vector<double>
39 operator()(boost::mpi::communicator const &comm) const override {
40 auto const &lb = System::get_system().lb;
41 auto const pressure_conv = 1. / (lb.get_agrid() * Utils::sqr(lb.get_tau()));
42 auto const local_tensor = lb.get_pressure_tensor() * pressure_conv;
43 std::remove_const_t<decltype(local_tensor)> tensor;
44 boost::mpi::reduce(comm, local_tensor, tensor, std::plus<>(), 0);
45 return tensor.as_vector();
46 }
47};
48
49} // Namespace Observables
50
51#endif
std::vector< double > operator()(boost::mpi::communicator const &comm) const override
std::vector< std::size_t > shape() const override
Base class for observables.
System & get_system()
DEVICE_QUALIFIER constexpr T sqr(T x)
Calculates the SQuaRe of x.
Definition sqr.hpp:28
Utils::VectorXd< 9 > get_pressure_tensor() const