Journal of Fluid Mechanics

Minimum error solutions of the Boltzmann equation for shock structure

R.  Narasimha a1 and S. M.  Deshpande a1
a1 Department of Aeronautical Engineering, Indian Institute of Science, Bangalore 12

Article author query
narasimha r   [Google Scholar] 
deshpande sm   [Google Scholar] 


‘Best’ solutions for the shock-structure problem are obtained by solving the Boltzmann equation for a rigid sphere gas by applying minimum error criteria on the Mott-Smith ansatz. The use of two such criteria minimizing respectively the local and total errors, as well as independent computations of the remaining error, establish the high accuracy of the solutions, although it is shown that the Mott-Smith distribution is not an exact solution of the Boltzmann equation even at infinite Mach number. The minimum local error method is found to be particularly simple and efficient. Adopting the present solutions as the standard of comparison, it is found that the widely used v2x-moment solutions can be as much as a third in error, but that results based on Rosen's method provide good approximations. Finally, it is shown that if the Maxwell mean free path on the hot side of the shock is chosen as the scaling length, the value of the density-slope shock thickness is relatively insensitive to the intermolecular potential. A comparison is made on this basis of present results with experiment, and very satisfactory quantitative agreement is obtained.

(Published Online March 29 2006)
(Received August 20 1968)