scholarly journals Ecological and evolutionary dynamics in advective environments: Critical domain size and boundary conditions

2021 ◽  
Vol 26 (1) ◽  
pp. 367-400
Author(s):  
Wenrui Hao ◽  
◽  
King-Yeung Lam ◽  
Yuan Lou ◽  
Keyword(s):  
Boundary Conditions ◽  
Evolutionary Dynamics ◽  
Domain Size ◽  
Critical Domain

Computational investigation of turbulent jet impinging onto rotating disk

2007 ◽  
Vol 17 (3) ◽  
pp. 284-301 ◽  
Author(s):  
A.C. Benim ◽  
K. Ozkan ◽  
M. Cagan ◽  
D. Gunes
Keyword(s):  
Boundary Conditions ◽  
Isotropic Turbulence ◽  
Domain Size ◽  
Rotating Disk ◽  
Turbulent Jet ◽  
Turbulence Structure ◽  
Computational Domain ◽  
Convergence Criteria ◽  
Computational Investigation ◽  
Content Type

PurposeThe main purpose of the paper is the validation of a broad range of RANS turbulence models, for the prediction of flow and heat transfer, for a broad range of boundary conditions and geometrical configurations, for this class of problems.Design/methodology/approachTwo‐ and three‐dimensional computations are performed using a general‐purpose CFD code based on a finite volume method and a pressure‐correction formulation. Special attention is paid to achieve a high numerical accuracy by applying second order discretization schemes and stringent convergence criteria, as well as performing sensitivity studies with respect to the grid resolution, computational domain size and boundary conditions. Results are assessed by comparing the predictions with the measurements available in the literature.FindingsA rather unsatisfactory performance of the Reynolds stress model is observed, in general, although the contrary has been expected in this rotating flow, exhibiting a predominantly non‐isotropic turbulence structure. The best overall agreement with the experiments is obtained by the k‐ω model, where the SST model is also observed to provide a quite good performance, which is close to that of the k‐ω model, for most of the investigated cases.Originality/valueTo date, computational investigation of turbulent jet impinging on to “rotating” disk has not received much attention. To the best of the authors' knowledge, a thorough numerical analysis of the generic problem comparable with present study has not yet been attempted.

Investigation of Annular Jet Flows in a Subsonic Air-Air Ejector With Multi-Ring Entraining Diffuser

2015 ◽  
Author(s):  
A. Namet-Allah ◽  
A. M. Birk
Keyword(s):  
Boundary Conditions ◽  
Turbulence Model ◽  
Nozzle Exit ◽  
Turbulence Models ◽  
Domain Size ◽  
Pressure Recovery ◽  
Cfd Simulations ◽  
The Core ◽  
Measured Flow ◽  
Air Ejector

The current paper presents a cold flow simulation study of a low Mach number air-air ejector with a four ring entraining diffuser that is used in a variety of applications including infrared (IR) suppression of exhaust from helicopters and fixed wing aircraft. The main objectives of this investigation were to identify key issues that must be addressed in successful CFD modelling of such devices, and recognize opportunities to improve the performance of these devices. Two-dimensional CFD simulations were carried out using commercial software, Ansys14. Studies of mesh and domain size sensitivity were made to ensure the CFD results were independent of both factors. A turbulence model independence study using k-ε, k-ω and RSM turbulence models was performed to figure out the appropriate turbulence model that produced the best agreement with the experimental data for several of ejector performance criteria. The measured flow properties in the annulus were used as input boundary conditions for the CFD simulations. However, in the comprehensive turbulence model study, the measured flow parameters at the nozzle exit were also applied as inlet boundary conditions for the CFD simulations. The measured flow velocity at the nozzle exit, at one centerline section inside the mixing tube and at the diffuser exit and the system pressure recovery were compared with the CFD predictions. The ejector pumping ratios, back pressure coefficient and diffuser gap velocities were also compared. It was found that the RANS-based CFD predictions were sensitive to the changes in the ejector domain size, mesh refinement and inlet boundary condition locations. With the annulus inlet boundary conditions, the tested turbulence models under predicted the size of the core separation downstream of the system, back pressure, pumping ratio and pressure recovery in the mixing tube and diffuser. However, the ability of the RNG turbulence model to predict the ejector performance parameters was better than that of the other turbulence models at all inlet flow conditions. Nevertheless, applying the inlet boundary conditions at the nozzle exit enhanced the capability of the RANS-based turbulence model particularly in predicting the ejector pumping ratios, pressure recovery and the size of the core separation. Finally, the acceptable agreement between the experimental data and the CFD predictions provides a valid tool to continue improving these devices using CFD techniques.

scholarly journals Multiscale Modelling of Vascular Tumour Growth in 3D: The Roles of Domain Size and Boundary Conditions

PLoS ONE ◽  
2011 ◽  
Vol 6 (4) ◽  
pp. e14790 ◽  
Author(s):  
Holger Perfahl ◽  
Helen M. Byrne ◽  
Tingan Chen ◽  
Veronica Estrella ◽  
Tomás Alarcón ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Tumour Growth ◽  
Domain Size ◽  
Multiscale Modelling ◽  
Vascular Tumour

scholarly journals Approximating the Critical Domain Size of Integrodifference Equations

2015 ◽  
Vol 78 (1) ◽  
pp. 72-109 ◽  
Author(s):  
Jody R. Reimer ◽  
Michael B. Bonsall ◽  
Philip K. Maini
Keyword(s):  
Domain Size ◽  
Integrodifference Equations ◽  
Critical Domain
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