Comparison of CFD Simulation to the Experiments for Forward Step Flows

2003 ◽  
Author(s):  
Shoichiro Nakamura ◽  
Hiroyuki Onuma ◽  
Peter G. Carswell
Keyword(s):  
Fluid Flow ◽  
Vortex Shedding ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Unsteady Motion ◽  
Computational Results ◽  
Over The Top ◽  
Unsteady Behavior

Three dimensional DNS simulation on the fluid flow over a forward step configuration are compared with the experiments reported by Shakouchi, Ando, and Ito. This is a part of authors’ attempts to evaluate the validity of three dimensional unsteady flow simulation by comparison to experiments. Summary of the comparison is as follows: (1) vortex shedding in the flow separation over the top of the step near the corner is observed, (2) frequency of vortex shedding and distance between two consecutive vortices do not agree with the experiment, (3) however, while steady periodic shedding of vortices from the top corner of the step is reported for the experimental results, the computational results show unsteady behavior of the flow over the top corner, which results in unsteady shedding of vortices. This unsteadiness in the computational simulation is due to unsteady motion of fluid upstream from the step where adverse pressure increase occurs.

scholarly journals Three-Dimensional Modeling and Fluid Flow Simulation for the Quantitative Description of Permeability Anisotropy in Tidal Flat Carbonate

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5557
Author(s):  
Hassan A. Eltom ◽  
Nabil A. Saraih ◽  
Oliver G. Esteva ◽  
Lundi Kusuma ◽  
Saleh Ahmed ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Tidal Flat ◽  
Three Dimensional ◽  
Flow Simulation ◽  
3D Models ◽  
Depositional Environments ◽  
High Permeability ◽  
Stratigraphic Framework ◽  
Permeability Anisotropy ◽  
Lithofacies Association

Three-dimensional (3D) facies and petrophysical models were generated from previously published data of carbonate strata in the Dam Formation (eastern Saudi Arabia) to quantitatively investigate, describe, understand, model, and predict the permeability anisotropy in tidal flat carbonate on the basis of a sequence stratigraphic framework. The resulting 3D models were used to conduct fluid flow simulations to demonstrate how permeability anisotropy influences the production of hydrocarbons and ultimately affects decisions concerning future drilling in the exploration and development of carbonate reservoirs with tidal flat strata. The constructed 3D facies model consists of four lithofacies associations, two of which are grain-dominated associations and two of which are mud-dominated associations. These lithofacies associations vary spatially in four reservoir zones (zones 1 to 4), which represent two fourth-order sequences in the uppermost part of the Dam Formation. Zones 1 and 3 consist of transgressive parasequences, and zones 2 and 4 consist of the regressive parasequences of these sequences. The 3D porosity and permeability models have a coherent match with the distribution of the lithofacies and the stratigraphic framework of the Dam Formation. The results suggest that the permeability anisotropy in zones 1 and 3 is controlled by the occurrence of the grain-dominated lithofacies associated with tidal flat channels. This lithofacies association overlies the sequence boundaries of sequences 1 and 3, forms reservoir bodies with relatively high permeability values, and is elongated perpendicular to the shoreline of the depositional environment. In contrast, permeability anisotropy in zones 2 and 4 is thought to be controlled by the occurrence of the grain-dominated lithofacies associated with the oolitic shoal. This lithofacies association overlies the maximum flooding surface of sequences 2 and 4, forms reservoir bodies with relatively high permeability values, and is elongated parallel to the shoreline of the depositional environments. Fluid flow simulation results suggest that the trend in hydrocarbon production from the constructed 3D models depends on permeability anisotropy in each reservoir zone. Thus, recognizing trends in permeability anisotropy, which can be predicted using sequence stratigraphy, could help to identify potential areas for future drilling.

scholarly journals Unsteady CFD simulation of 3D AUV hull at different angles of attack

2016 ◽  
Vol 13 (2) ◽  
pp. 111-123
Author(s):  
Sudipta Ray ◽  
Dipankar Chatterjee ◽  
Sambhunath Nandy
Keyword(s):  
Cfd Simulation ◽  
Autonomous Underwater Vehicle ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Underwater Vehicle ◽  
Three Dimensional Flow ◽  
Pressure Coefficients ◽  
Hydrodynamic Parameters ◽  
Sst Turbulence Model

An unsteady, three-dimensional flow simulation is carried out over the bare hull of the autonomous underwater vehicle currently being developed by CSIR-CMERI, Durgapur, India at various angles of attack with the help of a Finite Volume-based CFD software. The purpose of the study is to provide estimation of various hydrodynamic forces acting on the bare hull at different angles of operation. The operating range of velocity of the vehicle is 0-6 knot (0-3 m/s), considering up to 2 knots of upstream current. For the purpose of the CFD simulation, the widely-implemented RANS approach is used, wherein the turbulent transport equations are solved using the low-Re version of the SST ?-? turbulence model. The motion of the vehicle is considered within a range of the pitch angle (0<=alpha<=20). The results are presented in terms of variations of the relevant hydrodynamic parameters. The effects of the angle of attack on the drag and pressure coefficients are discussed in detail.

Off Set Strip Fins Thermo Hydraulic Performance Analysis Through CFD Simulation

2013 ◽  
Author(s):  
Guisselle Polo ◽  
Antonio Bula
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Hydraulic Performance ◽  
Constant Flow ◽  
Uniform Temperature ◽  
Colburn Factor ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin (OSF) is performed. The simulations are carried for Reynolds number ranging from 300 to 9000 considering three-dimensional conditions (3D). Calculations were developed assuming a constant flow. Colburn factor j, and the friction factor f, were calculated. Uniform temperature condition is assumed at the solid surface and at the inlet. The results have been compared with studies made by Kays and London, (1984), Manglik and Bergles (1990), and Muzychka and Yovanovich, (2001). According to the obtained results, it can be concluded that Computational Fluid Dynamics (CFD) is able to explore the behavior and performance of this kind of fin, showing that the hydraulic performance is well represented by correlations widely used in literature, while thermal performance seems to be under predicted.

Determination of Outside Heating Distribution Using an Inverse Algorithm for an Industry Hydrothermal Autoclave With Three-Dimensional Flows

2004 ◽  
Author(s):  
Hongmin Li ◽  
Minel J. Braun ◽  
G.-X. Wang ◽  
Edward A. Evans
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Heat Conduction ◽  
Flux Distribution ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Heat Flux Distribution ◽  
Inverse Algorithm ◽  
Small Magnitude

Hydrothermal growth is the industry method of preference to obtain high quality single crystals. Due to the high pressure and high temperature growth conditions, growth process is carried out in closed containers. During a growth run, the only flow and heat transfer that control crystal growers have is the outside heating. An inverse algorithm, used to obtain the heating distribution for an autoclave with a two-dimensional flow, is further developed and used to determine the heating distribution for an industry autoclave with three-dimensional flows. A cross-section area average temperature distribution is set as a target. With the three steps, including CFD simulation of the fluid flow, heat conduction in the metal wall, and heat conduction in the insulation layer, the heater heat flux distribution is determined. The distributions appear close to linear from the median height to the top/bottom with small magnitude deviation in the circumferential direction. Linearly distributed heaters, based on the determined heat flux distribution, are then used and heat transfer and fluid flow is numerically simulated with a conjugate model. The achieved temperature agrees well with the targeted one. The distribution and heating rates of linearly distributed heaters can be applied to industry autoclaves.

scholarly journals CFD Simulation of Aeration and Mixing Processes in a Full-Scale Oxidation Ditch

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1633 ◽  
Author(s):  
Thomas Höhne ◽  
Tural Mamedov
Keyword(s):  
Fluid Flow ◽  
Cfd Simulation ◽  
Pure Water ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Full Scale ◽  
Solid Particles ◽  
Mixing Processes ◽  
Treatment Processes ◽  
Sst Turbulence Model

This study aims to build a computational fluid dynamics (CFD) model that can be used to predict fluid flow pattern and to analyse the mixing process in a full-scale OD. CFD is a widely used numerical tool for analysing, modelling and simulating fluid flow patterns in wastewater treatment processes. In this study, a three-dimensional (3D) computational geometry was used, and the Eulerian-Eulerian multiphase flow model was built. Pure water was considered as the continuous phase, whereas air was modelled as the dispersed phase. The Shear Stress Transport (SST) turbulence model was specified which predicts turbulence eddies in free stream and wall-bounded region with high accuracy. The momentum source term approach and the transient rotor-stator approach were implemented for the modelling of the submersible agitators. The hydrodynamic analysis was successfully performed for four different scenarios. In order to prevent the incorrect positioning of the submerged agitators, thrust analysis was also done. The results show that the minimum required water velocity was reached to maintain the solid particles suspended in the liquid media and adequate mixing was determined.

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