EVALUATION OF A HIGHER-ORDER IMMERSED BOUNDARY METHOD FOR VISCOUS FLOWS AND FLUID STRUCTURE INTERACTIONIMMERSED BOUNDARY METHODS (IBMS) HAVE REACHED A LEVEL OF MATURITY TO A POINT WHERE THEY ARE BEING FREQUENTLY EMPLOYED FOR SPECIFIC REAL WORLD APPLICATIONS WITHIN NASA. THE PRIMARY SHORTCOMING OF CARTESIAN MESH IBMS IS THE INABILITY OF EFFICIENTLY RESOLVING THIN BOUNDARY LAYERS FOR HIGH-REYNOLDS NUMBER FLOWS. THE INEFFICIENCY OF RESOLVING THIN VISCOUS FLOW REGIONS NEAR WALLS IS ASSOCIATED WITH THE CONSTANT ASPECT RATIO CARTESIAN GRID CELLS WHEREAS CONVENTIONAL CFD APPROACHES RELY ON BODY-FITTED HIGH ASPECT RATIO CELLS NEAR THE WALL TO RESOLVE LARGE GRADIENTS. IN THE PROPOSED RESEARCH NEW WALL MODELING APPROACHES(OR VISCOUS WALL EXTENSIONS) COUPLED WITH AN IBM ARE BEING EVALUATED TO ACCOUNT FOR THE VISCOUS BOUNDARY LAYER INTERACTING WITH THE SOLUTION AWAY FROM THE WALLS. DIFFERENT WALL MODELING APPROACHES PROPOSED IN PREVIOUS RESEARCH STUDIES ARE ALSO ADDRESSED AND COMPAREDTO THE PRESENTED APPROACHES. IN CONTRAST TO COMMON WALL-MODELING APPROACHES THAT USUALLY ONLY UTILIZE LOCAL FLOW INFORMATION THE PURSUED METHOD KEEPS THE HISTORY OF THEBOUNDARY LAYER. THIS IS WHY THIS METHOD MAY STILL BE EFFECTIVE AT MUCH LARGER Y+ VALUES THAN LOCAL WALL MODELING APPROACHES. AFTER ANALYZING THESE METHODS THEORETICALLY THEY ARE APPLIED TO INCREASINGLY MORE CHALLENGING FLOW FIELDS INCLUDING FULLY ATTACHED SEPARATED AND SHOCK-INDUCED SEPARATED (LAMINAR AND TURBULENT) FLOWS.IN THE SECOND PART OF THIS PROPOSED WORK THE IBM BY BREHM ET AL. [10 12] IS EVALUTATED FOR MOVING BOUNDARY AND FLUID-STRUCTURE INTERACTION PROBLEMS. THE NOVELTY OF THIS APPROACHIS TO EMPLOY LOCALLY STABILIZED HIGHER-ORDER ACCURATE FINITE-DIFFERENCE STENCILS. THE ROBUSTNESS OF THIS NEW IBM WAS DEMONSTRATED FOR A WIDE RANGE OF FLOW REGIMES FROM SUBSONIC TO HYPERSONIC FLOWS. THE KEY ADVANTAGE OF IBMS IS THAT THE COMPUTATIONAL MESHES CAN AUTOMATICALLY BE GENERATED STARTING FROM A WATER TIGHT SURFACE TRIANGULATION INDEPENDENT OF THE COMPLEXITY OF THE GEOMETRY. MOREOVER FOR FLOWS CONTAINING MOVING BOUNDARIES IBMS FACILITATE THE NUMERICAL SOLUTION PROCEDURE BY SOLVING THE GOVERNING EQUATIONS ON A STATIONARY NON-DEFORMING CARTESIAN GRID. IN CONTRAST CONVENTIONAL BODY-FITTED GRID APPROACHESARE CONFRONTED WITH IMMENSE DIFFICULTIES IN THE SOLUTION PROCEDURE ESPECIALLY FOR FLUID-STRUCTURE PROBLEMS WITH LARGE BOUNDARY DISPLACEMENTS. IN THIS RESEARCH THE IBM BYBREHM ET AL. [10 12] IS EXTENDED TO ACCOUNT FOR ALL ASPECTS THAT ARE INVOLVED WHEN CONDUCTING CFD SIMULATIONS INCLUDING UNSTEADY BOUNDARY MOTION AND FLUID STRUCTURE INTERACTION. THE ENHANCED IBM WHICH IS APPLIED TO THE COMPRESSIBLE NAVIER-STOKES EQUATIONS WILL BE RIGOROUSLY VALIDATED AND TESTED CONSIDERING WELL-DOCUMENTED MOVING BOUNDARY AND FLUIDSTRUCTURE INTERACTION PROBLEMS INCLUDING THOSE WITH FLOW DISCONTINUITIES.