Coarse-grained modeling of thermochemical nonequilibrium using the multigroup maximum entropy quadratic formulation

Area of Science:

• Computational fluid dynamics
• Aerospace engineering
• Chemical kinetics

Background:

• High-enthalpy flows exhibit complex nonequilibrium phenomena.
• Accurate modeling of internal energy-state populations is crucial for predicting flow behavior.
• Existing models can be computationally expensive.

Purpose of the Study:

• To develop a reduced-order model for high-enthalpy nonequilibrium flows.
• To improve the accuracy and efficiency of simulating internal energy-state distributions.
• To enable cost-effective analysis of hypersonic flight conditions.

Main Methods:

• A multigroup maximum entropy formulation was employed.
• Internal energy levels were grouped, and a piecewise quadratic representation was sought.
• The method of moments was used in conjunction with the maximum entropy principle.
• Higher-order polynomial reconstructions were compared to linear ones.

Main Results:

• The higher-order reconstruction accurately represents the logarithm of the population distribution function.
• A modest increase in computational cost yielded a more accurate representation.
• The model successfully captured nonequilibrium distribution dynamics with as few as three groups.
• Reduced computational costs were achieved for nonequilibrium flow simulations.

Conclusions:

• The developed reduced-order model provides an accurate and efficient approach for high-enthalpy nonequilibrium flows.
• The multigroup maximum entropy method offers a viable strategy for complex flow simulations.
• This approach is particularly beneficial for hypersonic flight applications.