Recent Enhancements To The FUN3D Flow Solver For Moving-Mesh Applications

An unsteady Reynolds-averaged Navier-Stokes solver for unstructured grids has been extended to handle general mesh movement involving rigid, deforming, and overset meshes. Mesh deformation is achieved through analogy to elastic media by solving the linear elasticity equations. A general method for specifying the motion of moving bodies within the mesh has been implemented that allows for inherited motion through parent-child relationships, enabling simulations involving multiple moving bodies. Several example calculations are shown to illustrate the range of potential applications. For problems in which an isolated body is rotating with a fixed rate, a noninertial reference-frame formulation is available. An example calculation for a tilt-wing rotor is used to demonstrate that the time-dependent moving grid and noninertial formulations produce the same results in the limit of zero time-step size. Nomenclature [Φ] state-transition matrix [Θ] convolution integral of [Φ] α angle of attack τ ̄ stress tensor F ̄ flux tensor I ̄ identity tensor δ structural displacement F̂a generalized aerodynamic force n ̂ unit (normal) vector Ω rotation vector Q control-volume average of q q vector of conserved variables or generalized coor-dinates R radial vector u mesh point displacement W control volume face velocity xi = (q, q̇)T vector of generalized displacements and ve-locities, ith mode ν Poisson’s ratio ωi natural frequency of ith mode φi(x) ith mode shape φn coefficients for backward time differencing E Young’s modulus R residual t nondimensional time V control volume [Tm] 4x4 transform matrix CG center of gravity GCL Geometric Conservation La