3D Euler Smooth#

This problem solves the 3D Euler equations in conservative form for a smooth field. The gas dynamics is governed by a system of PDE

\[\begin{split}\frac{\partial }{\partial t} \begin{bmatrix}\rho \\ \rho u_x \\ \rho u_y \\ \rho u_z\\ \rho E \end{bmatrix} + \frac{\partial }{\partial x} \begin{bmatrix}\rho u_x \\ \rho u_x^2 +p \\ \rho u_x u_y \\ \rho u_x u_z\\ (\rho E+p)u_x \end{bmatrix} + \frac{\partial }{\partial y} \begin{bmatrix}\rho u_y \\ \rho u_x u_y \\ \rho u_y^2 +p \\ \rho u_y u_z\\ (\rho E+p)u_y \end{bmatrix} + \frac{\partial }{\partial z} \begin{bmatrix}\rho u_z \\ \rho u_x u_z \\ \rho u_y u_z \\ \rho u_z^2 +p\\ (\rho E+p)u_z \end{bmatrix}= 0\end{split}\]

where the pressure \(p\) is related to the conserved quantities through the equation of the state

\[p=(\gamma -1)(\rho E-\frac{1}{2}\rho (u_x^2 + u_y^2 + u_z^2)).\]

  • Initial conditions (primitive variables):

    • \(\rho = 1 + 0.2\sin(\pi (x+y+z))\)

    • \(u = 1, v = 1, w = 1, p = 1\)

    • These are used to create the initial conditions in conservative variables.

  • By default, \(\gamma = 1.4\)

  • Domain is \([-1, 1]^3\) with periodic BC

  • Analytical density as function of time is given as: \(\rho(t) = 1 + 0.2\sin(\pi (x+y+z - 3 t))\)

  • Typically, integration is performed for \(t \in (0, 2)\)

  • The problem is adopted from this paper:

    • in the original paper, they used \(v = -0.5\), while we use \(v = 1\)

Caution

Currently, this problem only works for first order and Weno3 inviscid flux reconstruction.

Mesh#

python3 pressio-demoapps/meshing_scripts/create_full_mesh_for.py \
        --problem euler3dsmooth_s<stencilSize> -n Nx Ny Nz --outDir <destination-path>

where

  • Nx, Ny, Nz is the number of cells you want along \(x\), \(y\), \(z\) respectively

  • <stencilSize> = 3 or 5: defines the neighboring connectivity of each cell

  • <destination-path>: full path to where you want the mesh files to be generated. The script creates the directory if it does not exist.

Important

When you set the <stencilSize>, keep in mind the following constraints (more on this below):

  • InviscidFluxReconstruction::FirstOrder requires <stencilSize> >= 3

  • InviscidFluxReconstruction::Weno3 requires <stencilSize> >= 5

C++ synopsis#

#include "pressiodemoapps/euler3d.hpp"

int main(){
  namespace pda = pressiodemoapps;

  const auto meshObj = pda::load_cellcentered_uniform_mesh_eigen("path-to-mesh");

  const auto probId = pda::Euler3d::PeriodicSmooth;
  const auto scheme = pda::InviscidFluxReconstruction::FirstOrder; //or Weno3
  auto problem      = pda::create_problem_eigen(meshObj, probId, scheme);
  auto state      = problem.initialCondition();
}

Python synopsis#

import pressiodemoapps as pda

meshObj = pda.load_cellcentered_uniform_mesh("path-to-mesh")

probId  = pda.Euler3d.PeriodicSmooth
scheme  = pda.InviscidFluxReconstruction.FirstOrder # or Weno3
problem = pda.create_problem(meshObj, probId, scheme)
state   = problem.initialCondition()