**Description**
Atmospheric re-entry vehicles have wing-body configuration with blunt leading edges on wings and slender fuselage. These vehicles pass through several phases of flight during ascent / descent and therefore their aerodynamic performance parameters vary from rarefied flow conditions to hypersonic continuum flow to subsonic speeds before final full stop. Measurement of temperatures on hot spots in hypersonic flow remained a challenge for a mankind. Re-entry vehicle covers wide range of Mach, angles of attack, angles of side slip and control surface deflections during its complete mission profile. A bow shock forms ahead of the vehicle to slow down the hypersonic flow. Apart from the blunt-shaped nose, the most recent re-entry vehicles are equipped with ablative Thermal Protection Systems (TPS) to avoid possible damage of the capsule and insulate the vehicles content.
When a capsule re-enter an atmospheric environment, a strong shock wave is formed in front of it. Behind the shock wave, a shock layer with very high temperature appears where a high enthalpy fluid flows around a capsule, resulting in a severe heating environment. Moreover, in an environment where the capsule velocity exceeds 8 km/s such as a super-orbit re-entry, there appear complicated phenomena accompanied by the radiation and/or the influence of turbulence.
The computed results are utilized to determine whether the aero-thermodynamic loads exceed the allowable values. If the loads are exceeding, then an optimized design is required to account for these loads. Moreover, if it is not exceeding, further analysis is done on the other components to ensure their reliability.
Computational Fluid Dynamics is extensively used to simulate these flows, as high enthalpy and low density associated with the flight conditions are difficult to reproduce in wind tunnels or shock tunnels at each re-entry trajectory point. Wind and shock tunnel tests are difficult and are costly to conduct at high enthalpy conditions. CFD is a much more economical approach for studying such flows. Therefore, CFD is extensively used as an analysis tool in the design of hypersonic vehicles. CFD is also used as a research tool to understand the complicated hypersonic effects.

**Author(s) - ranked in descending order of contribution / as it should appear when published**
Er. Mahima



 Computational Fluid Dynamics analysis of re entry vehicle during atmospheric re entry

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