TCNEQ Version

Background

The following information relates to the use of the thermochemical nonequilibrium (TCNEQ) version of PHASTA written in terms of entropy variables. The reader is referred to the following for additional information.

• F. Chalot, T.J.R. Hughes, and F. Shakib, "Symmetrization of Conservation Laws with Entropy for High-Temperature Hypersonic Computations," Computing Systems in Engineering, 1(2-4):495–521, 1990.

• J. Pointer, "Influence of Interpolation Variables and Discontinuity Capturing Operators on Inviscid Hypersonic Flow Simulations Using a Stabilized Continuous Galerkin Solver," Ph.D. dissertation, University of Colorado, Boulder, CO, 2022.

Pre-Processing

Meshing

Within the Simmodeler utility, the mesh can either be created or loaded from an existing .cas file. Below are steps for loading a mesh from a .cas file:

1. Launch Simmodeler (for this example, SimModeler7.0-190604 is used)
2. File > Import Discrete Data > (select .cas file to import) > (keep defaults and click OK) > (select YES to keep volume mesh)
3. Save .sms and .smd files
4. Attributes can now be assigned to the model as normal

Boundary Conditions

Below are the recognized boundary conditions that can be applied for the current version:

• comp1/comp2/comp3 - Specification of one/two/three components of velocity, [m/s]
• temperature - Specification of translational-rotational temperature, [K]. By default, vibrational temperature is held in equilibrium with this value and nonequilibrium is controlled through simulation inputs.
• surfID - When value is set to 702, the boundary is treated as a slip wall. If using this option, include a boundary layer mesh along the surface to ensure the wall normal direction is accurately computed.
• scalar_1 - Mole fraction of species 2 of the gas
• scalar_2 - Mole fraction of species 3 of the gas
• scalar_3 - Mole fraction of species 4 of the gas
• scalar_4 - Mole fraction of species 5 of the gas
• pressure - Specification of static pressure over a surface, [Pa]
  • Used to compute mole fraction of species 1 of the gas with Dalton's Law of partial pressures and subtracting the summation of the other mole fractions from a value of 1
• heat flux - set to zero for adiabatic wall boundary condition

Initial Conditions

Below are the required initial conditions for the current version:

• initial velocity - Components and magnitude of flow velocity, [m/s]
  • If a supersonic outlet condition is used, set such that flow is initialized Mach > 1
• initial temperature - Value used to set translational-rotational temperature, [K]
• initial scalar_1 - Initial value of species 2 mole fraction
• initial scalar_2 - Initial value of species 3 mole fraction
• initial scalar_3 - Initial value of species 4 mole fraction
• initial scalar_4 - Initial value of species 5 mole fraction
• initial pressure - Static pressure of the gas, [Pa]
  • For multi-species flows, this value is used in combination with the initial scalar values to compute the mole fraction of species 1