DSMC simulation and experimental validation of shock interaction in hypersonic low density flow.

Area of Science:

• Aerospace Engineering
• Computational Fluid Dynamics
• Hypersonics

Background:

• Hypersonic flows present complex shock interactions.
• Low-density environments exacerbate simulation challenges.
• Accurate modeling of intermolecular collisions is crucial for Direct Simulation Monte Carlo (DSMC) methods.

Purpose of the Study:

• To develop and validate Direct Simulation Monte Carlo (DSMC) models for hypersonic shock interactions in low-density flows.
• To compare the performance of different molecular collision models (hard sphere, variable hard sphere, variable soft sphere) within DSMC simulations.
• To assess the impact of Knudsen number and intermolecular interaction models on simulation accuracy.

Main Methods:

• Direct Simulation Monte Carlo (DSMC) simulations were performed.
• Three molecular collision models were employed: hard sphere (HS), variable hard sphere (VHS), and variable soft sphere (VSS).
• Simulations covered double-cone and Edney's type IV hypersonic shock interactions in low-density flow.

Main Results:

• All three molecular models predicted trends for pressure coefficient and Stanton number in double-cone interactions.
• The HS model demonstrated the best agreement with experimental data for both double-cone and Edney's type IV shock interactions.
• DSMC errors were found to depend on the Knudsen number and the chosen intermolecular interaction model, decreasing with increasing Knudsen number.

Conclusions:

• The hard sphere (HS) molecular model provides the most accurate results for hypersonic shock interactions in low-density flows using DSMC.
• DSMC simulations with HS and VHS models show good agreement for Edney's type IV shock interactions, while VSS model performance is less reliable.
• Simulation accuracy is significantly influenced by the Knudsen number and intermolecular interaction models, with errors within 10% for Knudsen numbers around 10⁻⁴.