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Although extensive research has been conducted for turbulent single and offset wall jets, relatively little research has been conducted for turbulent parallel jets. Relevant applications include burners, boilers, film cooling, fuel-injection, heating and air-conditioning systems, and designs for pollutant exhaust stacks. The objective of the present work is to evaluate the use of Reynolds-averaged...
This paper compares the results and the computational efficiency of a research code with that of a commercial code on the same problem. The research code (REACT-MB) is tested using its unsteady hybrid large-eddy simulation/Reynolds-averaged Navier-Stokes (LES/RANS) method as well as a more common steady-state Menter RANS method. CFD++ of Metacomp is tested on the same problem using its realizable...
Despite efforts to maintain streamlined shapes for minimal resistance and noise, US Navy marine vehicles oftentimes must have bluff body geometries or must operate in off-design modes. These situations produce separated flows that are unsteady. At large scales the flow unsteadiness may be the cause of structural concerns while the entire range of fluid dynamic scales, from large to small, may be the...
Flight 1. A 7 degree sphere-cone fore body was employed to determine likely transition characteristics and location at different times in the flight path. The implications of a shroud encapsulating the vehicle on placement of the pitot tube were also investigated. Since ground-tests are a major component of the HIFiRE campaign, the effectiveness of large-eddy simulations (LES) in predicting isolator...
Implicit large-eddy simulation (ILES) computations have been performed for canonical problems associated with flexible, flapping-wing micro air vehicles (MAVs). This computationally-intensive approach, which is able to directly model laminar/transitional/turbulent flow fields, requires the use of the best high performance computational platforms available. Results for the direct numerical simulation...
Flow separation from lifting surfaces such as airfoils is undesirable as it deteriorates performance. For example, when airfoils that are designed for large Reynolds numbers are operated at smaller off-design Reynolds numbers, laminar separation can occur. Laminar separation typically leads to transition and reattachment. Transition is influenced by factors, such as free-stream turbulence and wall...
Flow separation is always three-dimensional despite the fact that most of the past research has focused on two-dimensional separation. The three-dimensional character of separation is particularly relevant when low-aspect ratio geometries are considered. Separation is often associated with unsteadiness, which is caused by large coherent structures that are a consequence of hydrodynamic instability...
This paper describes the efforts to model full three-dimensional unsteady loads due to aerodynamic, and engine exhaust effects for an AV-8B aircraft model. This study utilizes USM3D for baseline comparison, and a CREATE-AV product - Helios - to transition into an engineering prediction tool. The comparative advantages of the different aerodynamic load predict in codes involved, and the capability...
The primary purpose of our research efforts is to improve naval design and detection capabilities. Our current research efforts leverage high performance computing (HPC) resources to perform high-resolution numerical simulations with hundreds-of-millions to billions of unknowns to study wave breaking behind a transom stern, wave-impact loading, the generation of spray by high-speed planing craft,...
We present the numerical performance of orthogonal and biorthogonal wavelet-based parameterization schemes for solving parameter estimation problems for finding a global solution using the Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm. The two schemes are tested on a two-phase flow problem using the Integrated Parallel Accurate Reservoir Simulators (IPARS) simulator in MATLAB...
A computational study of the weapons bay acoustics characteristics on a geometry representative of the F-35 is currently underway to support the development of possible "control" strategies for the reduction of dynamic pressure loads in the weapons bay. Initial computations evaluate the wind-tunnel model design and establish a baseline of what is expected during the wind-tunnel testing....
In this paper, we describe the development of a parallel version of the IR3D (Incompressible Realistic 3-D) code, which simulates the environmental effects on the evolution of vortices trailing behind control surfaces of underwater vehicles. The objective of the project was to parallelize and optimize the existing implementation for clusters of multi-core nodes. The primary motivation was to reduce...
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