atl_eqn_LinearEuler_module Module

The linearized Euler equations of compressible inviscid flows.

These are the Euler equations but linearized around a global background state. In contrast to the nonlinear Euler equations in atl_eqn_euler_module, The state is represented in terms of the primitive variables density, velocity and pressure. To define the properties of the fluid the following parameters need to be defined:

• The isentropic expansion coefficient isen_coef
• The background state around the Euler equations are linearized each state variable needs to be given, and may be a function of time, see tem_load_temporal
• density the background density
• velocityX the background velocity in X direction
• velocityY the background velocity in Y direction
• If 3D: velocityZ for the background velocity in Z direction
• pressure the background pressure

Hence, the definition for the linearized euler equation takes a form like

  equation = {
    name   = 'linearEuler',
    isen_coef = 1.4,
    background = {
      density = 1.225,
      velocityX = 100.0,
      velocityY = 0.0,
      velocityZ = 0.0,
      pressure = 100000.0
    }
  }

The following equation names are implementing the linearized Euler equations:

• lineareuler
• lineareuler_2d