Shock Physics
In recent work I have examined the overstability of low Mach number shocks, extending previous numerical work to Mach numbers below 5. Feedback between the cooling region and the cold-dense-layer is a function of the Mach number, and may be quantified in terms of the reflection coefficient of sound waves in the general case. An important finding is that the stability properties of low Mach number shocks are dramatically altered if the shocked gas is able to cool below the temperature of the pre-shock gas. In such circumstances, low Mach number shocks behave in many ways as if they had higher Mach numbers. This work is relevant to the evolution of SNRs interacting with the hot phase of the ISM (e.g., in starbursts), and to shocks in dense molecular clouds.
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I have also examined the effect of cosmic rays and mass-loading on the thermal stability of flows.