A parallelized Lattice-Gas solver for transient Navier-Stokes-flow: Implementation and simulation results

The simple frigate shape (SFS) as defined by The Technical Co-operative Program (TTCP), is a simplified model of the frigate, which helps to investigate the basic flow fields of a frigate. In this paper, the flow fields of the different modified SFS models, consisting of a bluff body superstructure and the deck, were numerically studied. A parametric study was conducted by varying both the superstructure length L and width B to investigate the recirculation zone behind the hangar. The size and the position of the recirculation zones were compared between different models. The numerical simulation results show that the size and the location of the recirculation zone are significantly affected by the superstructure length and width. The results obtained by Reynolds-averaged Navier-Stokes method were also compared well with both the time averaged Improved Delayed Detached-Eddy Simulation results and the experimental data. In addition, by varying the model size and inflow velocity, various flow fields were numerically studied, which indicated that the changing of Reynolds number has tiny effect on the variation of the dimensionless size of the recirculation zone. The results in this study have certain reference value for the design of the frigate superstructure.

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The Differentiability of the Drag with Respect to the Variations of a Lipschitz Domain in a Navier--Stokes Flow

SIAM Journal on Control and Optimization ◽

10.1137/s0363012994278213 ◽

1997 ◽

Vol 35 (2) ◽

pp. 626-640 ◽

Cited By ~ 45

Author(s):

Juan Antonio Bello ◽

Enrique Fernández-Cara ◽

Jérôme Lemoine ◽

Jacques Simon

Keyword(s):

Stokes Flow ◽

Lipschitz Domain ◽

Navier Stokes

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A two-phase, two-dimensional, reacting parabolized Navier Stokes flow solver for the prediction of solid rocket motor flowfields

10.2514/6.1992-3600 ◽

1992 ◽

Cited By ~ 2

Author(s):

ALAN KAWASAKI ◽

DOUGLAS COATS ◽

DANIEL BERKER

Keyword(s):

Stokes Flow ◽

Rocket Motor ◽

Navier Stokes ◽

Two Dimensional ◽

Solid Rocket Motor ◽

Two Phase ◽

Flow Solver ◽

Solid Rocket

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Optimization of RANS Solver Simulation Setup for Propeller Open Water Performance Prediction

Volume 2: CFD and VIV ◽

10.1115/omae2015-41954 ◽

2015 ◽

Author(s):

Mohammed Islam ◽

Fatima Jahra ◽

Michael Doucet

Keyword(s):

Domain Size ◽

Open Water ◽

Fractional Factorial ◽

Navier Stokes ◽

Calm Water ◽

Simulation Results ◽

Open Water Performance ◽

Thrust And Torque ◽

Simulation Time ◽

Fixed Pitch

Mesh and domain optimization strategies for a RANS solver to accurately estimate the open water propulsive characteristics of fixed pitch propellers are proposed based on examining the effect of different mesh and computation domain parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations to be carried out in a limited memory environment, and in a timely manner; without compromising the accuracy of results. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of a fixed pitch propeller. The predicted thrust and torque for the propeller were compared to the corresponding measurements. A total of six meshing parameters were selected that could affect the computational results of propeller open water performance. A two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent parameters: namely simulation time, propeller thrust and propeller torque. A total of 32 simulations were carried out only to find out that the selected six meshing parameters were significant in defining the response parameters. Optimum values of each of the input parameters were obtained for the DOE technique and additional simulations were run with those parameters. The simulation results were validated using open water experimental results of the same propeller. It was found that with the optimized meshing arrangement, the propeller opens simulation time was reduced by at least a factor of 6 as compared to the generally popular meshing arrangement. Also, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using STAR-CCM+, a commercial CFD package; however the findings can be applied to any RANS solver.

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Direct simulation of evolution and control of three-dimensional instabilities in attachment-line boundary layers

Journal of Fluid Mechanics ◽

10.1017/s0022112095002746 ◽

1995 ◽

Vol 291 ◽

pp. 369-392 ◽

Cited By ~ 32

Author(s):

Ronald D. Joslin

Keyword(s):

Boundary Layer ◽

Stokes Equations ◽

Three Dimensional ◽

Plate Boundary ◽

Navier Stokes ◽

Two Dimensional ◽

Computationally Efficient ◽

Simulation Results ◽

Dimensional Simulation ◽

Attachment Line

The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier–Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic-source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in flat-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.

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