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Power-Augmented-Ram (PAR) and Vertical/Short Takeoff and Landing (V/STOL) vehicles use jet support at low speeds when the passive aerodynamic lift is not sufficient. Although V/STOL aircraft have been previously investigated, the PAR concept requires further understanding of the obliquely impinging jet. Previous modeling studies on jet impingement considered jets exiting from domain boundaries. However, many jet applications are not confined in the upward direction and require modeling of airflow entering the jet source. The unconfined jet, modeled as a ducted momentum source, is investigated in this work. The computational approach consists of a two-dimensional, steady, incompressible finite volume method utilizing the k-ε turbulence model. The numerical approach is validated for the planar turbulent free jet, jet normally impinging on the ground, and jet entering a channel under a ground-effect platform. New results are obtained for obliquely impinging jets moving along the ground. Flow structures are studied with focus on the upstream ground vortex, jet entrainment, downstream momentum flow, and effects of jet translating through a stagnant fluid. Beneficial aerodynamic configurations, which reduce ingestion and maximize downstream momentum flow, suggest small impingement angles and moderate ground distances.

Experimental design and optimization of innovative ground-effect transportation means is an iterative process which requires a large amount of time and resources. To avoid the large experimental expense, numerical modeling can be used to investigate Wing-in-Ground (WIG) vehicle flight. In this paper, modeling technique is applied for a two dimensional NACA 4412 airfoil in viscous flow in and out of ground effect. The numerical method consists of a steady state, incompressible, finite volume method utilizing the Spalart-Allmaras turbulence model. Grid generation and solution of the Navier-Stokes equations are completed using FLUENT 6.3. The modeling procedures are first validated against published experimental data for unbounded flow around an airfoil. Wing section aerodynamic characteristics are then studied for varying ground heights and two separate boundary conditions: fixed ground and moving ground. Ground effect calculations are compared to several previous studies, and our results are found to correlate with published aerodynamic trends in ground effect, although all studies appear to predict different magnitudes of aerodynamic forces.

Acoustic stimulation is a promising method for increasing drainage of non-Newtonian fluids through porous structures in various applications. In this study, a mathematical model is developed for unsteady flow of a bi-viscous incompressible fluid in a two-dimensional straight channel. Longitudinal vibrations are superimposed on the flow driven by pressure gradient along the channel. Simulations are carried out for a range of relevant dimensionless parameters. Effects of vibration amplitude, frequency, fluid viscosity ratio, channel width, and mean pressure gradient on the enhancement of mean flow rate are discussed.