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The interaction of a laser-generated plasma with a hemisphere cylinder at Mach 3.45 is simulated using the Euler equations and assuming a perfect gas. The instantaneous laser discharge is assumed to create a spherical region of heated gas upstream of the blunt body shock. The energy deposition generates a blast wave which propagates radially outwards. The heated region convects with the flow and interacts with the blunt body shock. The interaction results in a momentary decrease in the drag coefficient. The results are compared with experimental data of Adelgren et al for surface pressure. The peak pressure on the hemisphere due to the impact of the blast wave is matched in the simulation to estimate the thermal efficiency (i.e., the fraction of the laser discharge energy resulting in heating of the gas). The predicted centerline pressure vs time on the hemisphere is compared with the experimental data. The comparison indicates that the perfect gas Euler simulations with the assumed initial condition are incapable of accurately predicting the surface pressure and hence the net drag reduction. Nomenclaturec d Drag coefficient D Diameter of the hemisphere, m ∆E Laser discharge energy (simulation), J L Distance from focal point to hemisphere, m M Mach number p ∞ Freestream pressure, kg/m·s 2 Q Laser discharge energy (experiment), J r Radial coardinate, m r 0 Radius of the heated spot, m t Time, s T Temperature, K u Velocity vector of the fluid, m/s V Initial volume of heated region, m 3 x Axial coordinate, m ρ ∞ Freestream density, kg/m 3 θ Angle, degree τ Non-dimensional time ε Energy deposition parameter γ Heat capacity ratio

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