This work presents interpolation techniques for surface data resconstruction in immersed boundary methods. Immersed boundary methods allow the use of Cartesian grids and simple curvilinear non-body conforming grids that intersect the immersed body at multiple locations, and as a consequence, the estimation of surface properties becomes a non-trivial problem. This paper explores three techniques of surface data interpolation: Inverse Distance Weight(IDW), Inverse Distance Weight by Interpolation Point method(IDW-IP) and Inverse Distance Weight based on Upwinding(IDW-Upwind). These techniques have been applied to first order as well as higher order simulations of flow past NACA16009 airfoil at a Mach number of 0.75. Both mass conservative and fully interpolation based formulations of the immersed boundary method (Ghosh, S., Choi. J.-I., and Edwards, J. R., "Numerical Simulations of Effects of Micro Vortex Generators Using Immersed- Boundary Methods," AIAA Journal, Vol. 48, No. 1, Jan 2010, pp. 92-103) have been used. C_p plots indicate that surface data has noise, and it is more for the mass conservative formulation of the immersed-boundary method. In order to reduce noise present in the reconstructed surface pressure data, smoothing techniques such as moving average method and regression method have been investigated. The results obtained (C_l and C_d) have been compared with experimental data. Good agreement in C_l values is reported while C_d values have a relatively large error.
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