Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Richmond-Bryant, Jennifer

doi:10.1002/fld.568

Cited by 9 publications

(6 citation statements)

References 46 publications

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“…The system of equations is solved using FIDAP v.8.6.2 on an IBM 933 MHz processor PC, an SGI Origin 2400 with 48-400 MHz processors, and a Sun workstation with Ultra Sparc III dual 900 MHz processors. Details of the airflow simulation are described in Richmond-Bryant (2003a) and are summarized here. To take advantage of steady-state symmetry, the velocity field is solved over a half-plane, semi-circular grid.…”

Section: Rans Airflow Modelmentioning

confidence: 99%

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Richmond-Bryant

Eisner

Flynn

2006

Aerosol Science and Technology

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The objective of this work is to evaluate the performance of the steady state Reynolds Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) models for estimating concentration of low Stokes number aerosols (Stk = O(10 −4 )) in the wake of a bluff body. These simulations are compared with experimental data. In the simulations and experiments, particles are released upstream of the body and convected downstream, where some are entrained into the wake. The air velocity is computed using a steady state renormalized group k ∼ ε model. Lagrangian particle trajectory simulations are performed in conjunction with each airflow model to calculate concentrations. The experiments are performed in an aerosol wind tunnel in which phase Doppler velocimetry measurements are obtained the velocity field and for aerosol concentration.The RANS model yields a wake concentration deficit that extends downstream past x/D = 10, while the experiments produce elevated concentrations immediately downstream of the near wake. It is postulated that the concentration peak is at least in part attributed to particle interaction with the boundary layer by the following mechanism. Particles are transported into the boundary layer by turbulent diffusion, turbophoresis, and/or inertial forces. Particles then separate from the cylinder with the airflow and travel in a sheath around the periphery of the near wake to converge at the downstream edge of the near wake. Underestimation of the wake concentration by the RANS model is potentially due to inadequacy in the boundary layer approximation used in the model.

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Section: Rans Airflow Modelmentioning

confidence: 99%

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Richmond-Bryant

Eisner

Flynn

2006

Aerosol Science and Technology

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“…Within the wake region at x/D = 1.0 and x/D = 1.5, while some differences are observed between profiles obtained with t * = 0.002 and 0.001, predictions with a smaller time step of t * = 0.0005 do not significantly differ from those of t * = 0.001 . Moreover, with reference to the methodology discussed in Richmond-Bryant [13], global relative two-norm error for streamwise velocity is calculated for 5000 points located in the region −1 x/D 3, 0 y/D 1. The error resulting from increasing the time step from t * = 0.001 to t * = 0.002 is 6.03×10 −4 , and from t * = 0.0005 to t * = 0.001 is 2.06×10 −4 .…”

Section: Methodsmentioning

confidence: 99%

“…A further increase up to x u /D = 18.3 resulted in negligible changes. Richmond-Bryant [13] presented a numerical work providing a verification study of Reynoldsaveraged Navier-Stokes (RANS) methods for the problem of airflow past a circular cylinder at Re = 5232. She examined the standard and renormalized group (RNG) versions of the k-model, along with the Boussinesq [14] and Craft et al [15] stress strain-rate relation.…”

Section: Introductionmentioning

confidence: 99%

Two‐dimensional prediction of time dependent, turbulent flow around a square cylinder confined in a channel

Raisee

Jafari

Babaei

et al. 2009

Numerical Methods in Fluids

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SUMMARYThis paper presents two-dimensional and unsteady RANS computations of time dependent, periodic, turbulent flow around a square block. Two turbulence models are used: the Launder-Sharma low-Reynolds number k-model and a non-linear extension sensitive to the anisotropy of turbulence. The Reynolds number based on the free stream velocity and obstacle side is Re = 2.2×10 4 . The present numerical results have been obtained using a finite volume code that solves the governing equations in a vertical plane, located at the lateral mid-point of the channel. The pressure field is obtained with the SIMPLE algorithm. A bounded version of the third-order QUICK scheme is used for the convective terms. Comparisons of the numerical results with the experimental data indicate that a preliminary steady solution of the governing equations using the linear k-does not lead to correct flow field predictions in the wake region downstream of the square cylinder. Consequently, the time derivatives of dependent variables are included in the transport equations and are discretized using the second-order Crank-Nicolson scheme. The unsteady computations using the linear and non-linear k-models significantly improve the velocity field predictions. However, the linear k-shows a number of predictive deficiencies, even in unsteady flow computations, especially in the prediction of the turbulence field. The introduction of a non-linear k-model brings the two-dimensional unsteady predictions of the time-averaged velocity and turbulence fields and also the predicted values of the global parameters such as the Strouhal number and the drag coefficient to close agreement with the data.

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“…In addition to this, the isotropic eddy viscosity concept, on which the standard k − ε turbulence model is based, is known to produce unrealistically high turbulent kinetic energy (k) upstream of the bluff body that causes late separation and subsequent suppression of the near wake. (20,21) Therefore, the suitability of the standard k − ε turbulence model in conjunction with the standard wall function formulation is dubious and may point to further investigation.…”

Section: Introductionmentioning

confidence: 98%

On the Inconsistencies Related to Prediction of Flow into an Enclosing Hood Obstructed by a Worker

Karaismail

2010

Journal of Occupational and Environmental Hygiene

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The recirculating flow structures formed in the wake of a worker standing in front of an enclosing fume hood were numerically investigated. Two- and three-dimensional, unsteady, laminar/turbulent computations were performed for a Reynolds number (Re) range of 1.0 x 10(3)-1.0 x 10(5). The standard k-epsilon, Renormalization group (RNG) k-epsilon, and Shear Stress Transport (SST) k-omega models were used in Unsteady Reynolds Averaged Navier-Stokes (URANS) computations, and the results were compared with each other and also with the previous predictions reported in the literature. Numerical issues regarding the grid convergence and the inadequacies of turbulence models that may come into play at low Reynolds numbers were addressed. On the whole, SST k-omega model was found to be promising for qualitatively accurate prediction of both steady and unsteady recirculatory flow patterns in the wake of the worker. On the other hand, the standard and RNG k-epsilon models failed in prediction of anticipated unsteadiness at low Reynolds numbers. In a more realistic three-dimensional simulation with SST k-omega model, the anticipated unsteady and recirculating flow field in the wake of the worker was captured. Present results seem to qualitatively agree with the deductions made from experimental analyses in the literature while conflicting with some aspects of the previously reported numerical results. The apparent inconsistencies observed between the current results and those published in the literature were elucidated.

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Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Cited by 9 publications

References 46 publications

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Two‐dimensional prediction of time dependent, turbulent flow around a square cylinder confined in a channel

On the Inconsistencies Related to Prediction of Flow into an Enclosing Hood Obstructed by a Worker

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