On a New Model Reduction Method for CFD Systems Used for Flow Control Design

2013 ◽  
Vol 332 ◽  
pp. 9-14
Author(s):  
Adrian Mihail Stoica ◽  
Marius Stoia-Djeska
Keyword(s):  
Model Reduction ◽  
Flow Simulation ◽  
Type Systems ◽  
Discrete Systems ◽  
Navier Stokes ◽  
Governing Equations ◽  
Flow Solver ◽  
Efficient Control ◽  
Flow Domain ◽  
External Flows

The use of active control to get better characteristics of unsteady internal and external flows is the ultimate goal of the research presented in this paper. Usually, unsteady flows are calculated using Euler and/or Navier-Stokes solvers. The efficiency of numerical simulation of an unsteady flow dramatically increases if the unsteady solution is a small perturbation about a steady-state flow, due to disturbances occurring at the boundaries of the flow domain. The main difficulty related to the flow simulation is that any CFD (Computational Fluid Dynamics) technique generates discrete systems with a very large number of states. In order to design an efficient control, the flow solver must be not only accurate and numerically effective, but also it must have a low number of states. The aim of this paper is to present a new method for model reduction of CFD systems using representative governing equations. The focus is on descriptor type systems resulting from the spatial discretization of the CFD governing equations.

Wind Flow Simulation Around NASA KSC Vehicle Assembly Building

2004 ◽  
Author(s):  
B. T. Vu ◽  
M. J. Verdier
Keyword(s):  
Flow Field ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Wind Flow ◽  
Flow Solver ◽  
Wind Speeds ◽  
Velocity Magnitude ◽  
Operations And Maintenance ◽  
Kennedy Space ◽  
Detailed Mathematical Analysis

A model of the wind flow conditions around Kennedy Space Center (KSC) Vehicle Assembly Building (VAB) is presented. An incompressible Navier-Stokes flow solver was used to compute the flow field around fixed Launch Complex 39 (LC-39) buildings and structures. The 3-D flow field, including velocity magnitude and velocity vectors, was established to simulate the localized wind speeds and directions at specified locations in and around LC-39 buildings and structures. The results of this study not only help explain the physical phenomena of the flow patterns around LC-39 buildings but also are useful to the Shuttle personnel. Current Operations and Maintenance Requirements and Specifications (OMRS) for vehicle transfer operations are based on empirically derived historical data, and no detailed mathematical analysis of wind conditions around LC-39 structures has ever been accomplished.

scholarly journals GPU IMPLEMENTATION OF A VISCOUS FLOW SOLVER ON UNSTRUCTURED GRIDS

2016 ◽  
Vol 42 ◽  
pp. 1660167
Author(s):  
TIANHAO XU ◽  
LONG CHEN
Keyword(s):  
Graphics Processing Units ◽  
Stokes Equations ◽  
Unstructured Grids ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Competitive Advantages ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Volume Method ◽  
Graphics Processing

Graphics processing units have gained popularities in scientific computing over past several years due to their outstanding parallel computing capability. Computational fluid dynamics applications involve large amounts of calculations, therefore a latest GPU card is preferable of which the peak computing performance and memory bandwidth are much better than a contemporary high-end CPU. We herein focus on the detailed implementation of our GPU targeting Reynolds-averaged Navier-Stokes equations solver based on finite-volume method. The solver employs a vertex-centered scheme on unstructured grids for the sake of being capable of handling complex topologies. Multiple optimizations are carried out to improve the memory accessing performance and kernel utilization. Both steady and unsteady flow simulation cases are carried out using explicit Runge-Kutta scheme. The solver with GPU acceleration in this paper is demonstrated to have competitive advantages over the CPU targeting one.

Navier-Stokes Simulation of Air-Conditioning Facility of a Large Modern Computer Room

2005 ◽  
Author(s):  
Jasim U. Ahmad ◽  
Shishir A. Pandya ◽  
William M. Chan ◽  
Neal M. Chaderjian
Keyword(s):  
Air Conditioning ◽  
Large Scale ◽  
Flow Simulation ◽  
Navier Stokes ◽  
Flow Solver ◽  
Low Mach Number ◽  
Geometry Modeling ◽  
Modern Computer ◽  
Nasa Ames Research ◽  
Viscous Compressible Flow

A 3-D full Navier-Stokes simulation of a large scale computing facility at NASA Ames Research center was carried out to assess the adequacy of the existing air handling and conditioning system. The flow simulation of this modern facility was modeled with a viscous, compressible flow solver code OVERFLOW-2 with low Mach number pre-conditioning. A script was created to automate geometry modeling, grid generation, and flow solver input preparation. A new set of air-conditioning boundary conditions was developed and added to the flow solver. Detailed flow visualization was performed to show temperature distribution, air-flow streamlines and velocities in the computer room.

scholarly journals Computational Evaluation of Shock Wave Interaction with a Cylindrical Water Column

2021 ◽  
Vol 11 (11) ◽  
pp. 4934
Author(s):  
Viola Rossano ◽  
Giuliano De Stefano
Keyword(s):  
Shock Wave ◽  
Water Column ◽  
Wave Interaction ◽  
Navier Stokes ◽  
Plane Shock ◽  
Governing Equations ◽  
Computational Evaluation ◽  
Air Water Interface ◽  
The Mean ◽  
The Impact

Computational fluid dynamics was employed to predict the early stages of the aerodynamic breakup of a cylindrical water column, due to the impact of a traveling plane shock wave. The unsteady Reynolds-averaged Navier–Stokes approach was used to simulate the mean turbulent flow in a virtual shock tube device. The compressible flow governing equations were solved by means of a finite volume-based numerical method, where the volume of fluid technique was employed to track the air–water interface on the fixed numerical mesh. The present computational modeling approach for industrial gas dynamics applications was verified by making a comparison with reference experimental and numerical results for the same flow configuration. The engineering analysis of the shock–column interaction was performed in the shear-stripping regime, where an acceptably accurate prediction of the interface deformation was achieved. Both column flattening and sheet shearing at the column equator were correctly reproduced, along with the water body drift.

Computed Effects of Rotor-Induced Swirl on Brush Seal Performance—Part 2: Bristle Force Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 920-926 ◽  
Author(s):  
M. C. Sharatchandra ◽  
D. L. Rhode
Keyword(s):  
Inclination Angle ◽  
Flow Direction ◽  
Flow Simulation ◽  
Companion Paper ◽  
Navier Stokes ◽  
Brush Seal ◽  
Swirl Flows ◽  
Lift Off ◽  
Square Configuration ◽  
Periodic Module

This paper analytically investigates the aerodynamic bristle force distributions in brush seals used in aircraft gas turbine engines. These forces are responsible for the onset of bristle tip lift-off from the rotor surface which significantly affects brush seal performance. In order to provide an enhanced understanding of the mechanisms governing the bristle force distributions, a full Navier-Stokes flow simulation is performed in a streamwise periodic module of bristles corresponding to the staggered square configuration. As is the case with a companion paper (Sharatchandra and Rhode, 1996), this study has the novel feature of considering the combined effects of axial (leakage) and tangential (swirl) flows. Specifically, the effects of intra-bristle spacing and bristle inclination angle are explored. The results indicate that the lifting bristle force increases with reduced intra-bristle spacing and increased inclination angle. It was also observed that increases in the axial or tangential flow rates increased the force component in the normal as well as the flow direction.

Numerical Study of Wave Slamming on a Rectangular Slab

2012 ◽  
Vol 204-208 ◽  
pp. 4971-4977
Author(s):  
Ya Mei Lan ◽  
Wen Hua Guo ◽  
Yong Guo Li
Keyword(s):  
Numerical Study ◽  
Navier Stokes ◽  
Governing Equations ◽  
Reflected Waves ◽  
Rans Equations ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Wave Slamming ◽  
Numerical Wave ◽  
Rectangular Slab

The CFD software FLUENT was used as the foundation to develop the numerical wave flume, in which the governing equations are the Reynolds-averaged Navier-Stokes (RANS) equations and the standard k~ε turbulence model. The wave generating and absorbing were introduced into the RANS equations as the source terms using the relaxation approach. A new module of the wave generating and absorbing function, which is suitable for FLUENT based on the volume of fluid method (VOF), was established. Within the numerical wave flume, the reflected waves from the model within the computation domain can be absorbed effectively before second reflection appears due to the wave generating boundary. The computational results of the wave pressures on the bottom of the rectangular slab were validated for the different relative clearance by the experimental data. Good agreements were found.

Simulation of the Gap Resonance Between Two Rectangular Barges in Regular Waves by a Free Surface Viscous Flow Solver

2013 ◽  
Author(s):  
B. Elie ◽  
G. Reliquet ◽  
P.-E. Guillerm ◽  
O. Thilleul ◽  
P. Ferrant ◽  
...  
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Viscous Flow ◽  
Stokes Equations ◽  
Resonance Phenomenon ◽  
Navier Stokes ◽  
Regular Waves ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Gap Resonance

This paper compares numerical and experimental results in the study of the resonance phenomenon which appears between two side-by-side fixed barges for different sea-states. Simulations were performed using SWENSE (Spectral Wave Explicit Navier-Stokes Equations) approach and results are compared with experimental data on two fixed barges with different headings and bilges. Numerical results, obtained using the SWENSE approach, are able to predict both the frequency and the magnitude of the RAO functions.

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