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Two-phase flow phenomena inside a BWR fuel bundle include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. The CFD-BWR code is being developed as a specialized module built on the foundation of the commercial CFD code STAR-CD which provides general two-phase flow modeling capabilities. New models describing two-phase flow and heat transfer phenomena specific for BWRs are developed and implemented in the CFD-BWR module. A set of experiments focused on two-phase flow and phase-change...
The leading-edge tubercles of humpback whale flippers have been shown to enhance hydrodynamic performance by increasing lift and decreasing drag poststall. To explore this effect, computational simulations of two models based on an idealized humpback whale flipper were conducted, one with a smooth leading edge and one with simulated leading-edge tubercles. Two different commercial computational fluid dynamics packages were used, STAR-CCM+ and SolidWorks Flow Simulation, and the results were compared with experiment. Numeric lift predictions in the nonstall region were reasonably accurate (...
It is known that bioprosthetic heart valves (BHVs) have better hemodynamics and lower thromboembolic events compared with their mechanical counterparts; however, patients implanted with BHVs still face the potential of such complications. The risk of a clinical thromboembolism is on average 0.7% per year in patients with tissue valves in sinus rhythm. In this study, we developed a computational fluid dynamic (CFD) model of a BHV implanted in an aortic root and investigated the BHV-induced platelet activation using a damage accumulation model previously applied to mechanical valves. The CFD...
A newly developed computational approach different from the conventional methods which are popularly adapted by the fan designers is employed to study the flow field and performance characteristics of an axial flow fan by using the commercial code (STAR-CD) of computational fluid dynamics. The new approach, which is termed the "downstream flow resistance" (DFR) method, engages the flow resistance of the fan test bench in the downstream area of the computational domain. Both the static and moving grids are employed in the computation. The results show at least three emphases. Firstly, the...
This paper aims to improve current understanding of flow structure and particle deposition in asthmatic human airways. A single, symmetric airway bifurcation, corresponding to generations 10–11 of Weibel’s model, is investigated through validated numerical simulations. The parent airway segment is modelled as a smooth circular tube. The child segments are considered asthmatic and their cross-section is modelled as a constricted tube with sinusoidal folds uniformly distributed along the circumference. The flow structure and particle deposition pattern for normal (i.e., healthy) and asthmatic...
In conjunction with the NASA-Gulfstream and Gulfstream-University of Florida wind tunneltesting of a generic nose landing gear model, Computational Aero-Acoustics research was conducted at Gulfstream using the commercial Navier-Stokes Finite Volume CFD solver STAR-CCM+. The simulation modeled the ¼ scale G550 nose landing gear mounted in the NASA Basic Aerodynamics Research Tunnel (BART) wind tunnel test section. The model was run at the 0.166 Mach Number condition on the simplified nose landing gear with the gear cavity closed. Prior to simulation execution,dynamic pressure probes were...
A method is proposed to calculate the trailing-edge broadband noise emitted from an airfoil, based on a steady Reynolds-averaged Navier–Stokes solution of the flowfield. For this purpose, the pressure spectrum on the airfoil surface near the trailing edge is calculated using a statistical model from the Reynolds-averaged Navier–Stokes mean velocity and turbulence data in the airfoil boundary layer. The obtained wall-pressure spectrum is used to compute the radiated sound by means of an aeroacoustic analogy, namely, Amiet’s theory of airfoil sound. The statistical model for wall-pressure...
Transported probability density function (PDF) methods have been applied widely and effectively for modelling turbulent reacting flows. In most applications of PDF methods to date, Lagrangian particle Monte Carlo algorithms have been used to solve a modelled PDF transport equation. However, Lagrangian particle PDF methods are computationally intensive and are not readily integrated into conventional Eulerian computational fluid dynamics (CFD) codes. Eulerian field PDF methods have been proposed as an alternative. Here a systematic comparison is performed among three methods for solving the...
This paper compares two mean reaction rate closures for turbulent reacting flow: the Stochastic Fields (SF) method and the Direct Quadrature Method of Moments using the Interaction by Exchange with the Mean micromixing model (DQMoM-IEM). The methods have many common features and have received significant attention in recent literature, yet have not been systematically compared. We present both methods in the same mathematical framework and compare their numerical performance. In addition, we introduce antithetic sampling as a variance reduction technique to increase the efficiency of the SF...

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