Computational Fluid Dynamics-Based Hydrodynamics Studies in Packed Bed Columns: Current Status and Future Directions

2015 ◽  
Vol 13 (3) ◽  
pp. 289-303 ◽  
Author(s):  
Jameson Malang ◽  
Perumal Kumar ◽  
Agus Saptoro
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Pattern ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Packed Bed ◽  
Transfer Model ◽  
Number Range ◽  
Selection Of ◽  
Packed Bed Columns

Abstract A careful review of the literature reveals that extensive research has been done on the hydrodynamics in packed bed columns using turbulence models. It can be noted that the choice of turbulence model is influenced by the number of phases, type of fluid, Reynolds number range and the type of packing. Thus, comparison of turbulence models for the selection of a suitable model assumes great importance for the better prediction of flow pattern. This is due to the fact that poor prediction of the flow pattern can lead to a limited heat and mass transfer model as the rate of transfer processes in packed bed is governed by the hydrodynamics of the packed bed. The aim of this paper is to give a review of the computational fluid dynamics (CFD)-based hydrodynamics studies of packed bed columns with the primary interest of studying pressure drop and drag coefficient in packed beds. From the literature survey in Science Direct database, more than 48,000 papers related to packed bed columns have been published with more than 3,000 papers focused on the hydrodynamic studies of the bed to date. Unfortunately, there are only a few studies reported on the hydrodynamics of packed columns under supercritical fluid condition. Therefore, it is imperative that the future work has to focus on the hydrodynamics of supercritical packed column and particularly on the selection of suitable turbulence model.

scholarly journals Improving the quality of design calculations of viscous flow in low-flow centrifugal compressor stages by methods of computational fluid dynamics through reasonable application of different turbulence models

2021 ◽  
pp. 24-30
Author(s):  
S. V. Kartashev ◽  
◽  
Yu. V. Kozhukhov ◽  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Centrifugal Compressor ◽  
Turbulence Models ◽  
Low Flow ◽  
Solution Stability ◽  
Relative Width ◽  
Computational Domain

The paper considers the issue of improving the quality of the numerical experiment in the calculation of viscous gas in the flowing part of a low-flow centrifugal compressor stage. The choice of turbulence model in creating a calculation model for calculations by methods of computational fluid dynamics is substantiated. As object of research is chosen low-flow stage with conditional flow coefficient Ф=0,008 and relative width at impeller outlet b2 /D2 =0,0133. The issue of qualitative modeling of friction losses in low-flow stages is of fundamental importance and is directly related to the choice of turbulence model. It is shown that the choice of low-Reynolds turbulence models in the case of unloaded and discontinuous low-flow stages can be made from the main common models (SpalartAllmaras, SST, k-ω) based on the economy of calculations, speed of convergence, solution stability and adequacy of the obtained results. For models with wall functions, the quality of the mesh model and the observance of the dimensionless distance to the wall y+ throughout the calculation domain are particularly important. For highReynolds turbulence models, at values of y+=25...50 on all friction surfaces of the computational domain in the optimal mode of operation, the grid independence of the solution for the entire gas-dynamic characteristic is ensured. It is unacceptable for y+ to fall into the transition region of 4...15 between the viscous sublayer and the region of the logarithmic velocity profile

scholarly journals CFD Analysis of Golf Ball with Various Turbulence Models.

2021 ◽  
Vol 12 (1S) ◽  
pp. 491-497
Author(s):  
M.Sundararaj, Et. al.
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Rotational Motion ◽  
Research Work ◽  
Turbulence Models ◽  
Golf Ball ◽  
Cfd Analysis ◽  
Circular Arc ◽  
Motion Characteristics

In this research work we investigate the performance of golf ball with 256 circular arc dimples on golf ball. The turbulence characteristics and flow pattern over golf with various velocities investigated by computational fluid dynamics in suitable turbulence model, in addition that the distance covered by a ball and rotational motion characteristics also investigated with same turbulence model

Aerodynamic Subsonic Model at Transitional/Turbulent Reynolds Number for Bluff-Ellipsoidal Hulls

2020 ◽  
Author(s):  
Jorge A. Ricardo ◽  
Davi Antônio dos Santos ◽  
Elisan dos Santos Magalhães
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Computational Simulation ◽  
Superior Performance ◽  
Grid Turbulence ◽  
Aerodynamic Coefficients ◽  
Number Range ◽  
Turbulent Reynolds Number

Abstract The present work addresses the subsonic aerodynamic coefficients model for bluff ellipsoidal hulls at transitional and turbulent Reynolds number. The drag, lift, and moment aerodynamic coefficients model are based on computational fluid dynamics (CFD) simulations for four bluff ellipsoids with aspect ratio of 1, 2, 3, and 4, in the Reynolds number range of 1 × 103 to 2 × 106 and angle of attack range from 0 to 20 degrees. The Large Eddy Simulation (LES) turbulence model is used with the sub-grid turbulence model Wall-Adapting Local-Eddy Viscosity (WALE) to solve the fluid field. To reduce computational simulation time, at a first instant, the mesh is gradually refined until the point that it does not influence anymore in the final result (mesh independence). For each aerodynamic coefficient a nonlinear equation structure, valid for all the ellipsoids, is proposed as a parametric model with parameters estimated using the least mean square algorithm applied to the results of the computational fluid dynamics simulations. The proposed equations have a superior performance, in terms of precision and number of terms, when compared to polynomial equations fitted to the same data.

Computational Fluid Dynamics Simulation of Gasoline Compression Ignition

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Janardhan Kodavasal ◽  
Christopher P. Kolodziej ◽  
Stephen A. Ciatti ◽  
Sibendu Som
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Chemical Kinetic ◽  
Dynamics Simulation ◽  
Combustion Model ◽  
Compression Ignition ◽  
Simulation Results ◽  
The Impact

Gasoline compression ignition (GCI) is a low temperature combustion (LTC) concept that has been gaining increasing interest over the recent years owing to its potential to achieve diesel-like thermal efficiencies with significantly reduced engine-out nitrogen oxides (NOx) and soot emissions compared to diesel engines. In this work, closed-cycle computational fluid dynamics (CFD) simulations are performed of this combustion mode using a sector mesh in an effort to understand effects of model settings on simulation results. One goal of this work is to provide recommendations for grid resolution, combustion model, chemical kinetic mechanism, and turbulence model to accurately capture experimental combustion characteristics. Grid resolutions ranging from 0.7 mm to 0.1 mm minimum cell sizes were evaluated in conjunction with both Reynolds averaged Navier–Stokes (RANS) and large eddy simulation (LES) based turbulence models. Solution of chemical kinetics using the multizone approach is evaluated against the detailed approach of solving chemistry in every cell. The relatively small primary reference fuel (PRF) mechanism (48 species) used in this study is also evaluated against a larger 312-species gasoline mechanism. Based on these studies, the following model settings are chosen keeping in mind both accuracy and computation costs—0.175 mm minimum cell size grid, RANS turbulence model, 48-species PRF mechanism, and multizone chemistry solution with bin limits of 5 K in temperature and 0.05 in equivalence ratio. With these settings, the performance of the CFD model is evaluated against experimental results corresponding to a low load start of injection (SOI) timing sweep. The model is then exercised to investigate the effect of SOI on combustion phasing with constant intake valve closing (IVC) conditions and fueling over a range of SOI timings to isolate the impact of SOI on charge preparation and ignition. Simulation results indicate that there is an optimum SOI timing, in this case −30 deg aTDC (after top dead center), which results in the most stable combustion. Advancing injection with respect to this point leads to significant fuel mass burning in the colder squish region, leading to retarded phasing and ultimately misfire for SOI timings earlier than −42 deg aTDC. On the other hand, retarding injection beyond this optimum timing results in reduced residence time available for gasoline ignition kinetics, and also leads to retarded phasing, with misfire at SOI timings later than −15 deg aTDC.

scholarly journals Application of Computational Fluid Dynamics Method for Cross-flow Turbine in Pico Scale

2021 ◽  
Vol 6 (1) ◽  
pp. 1-8
Author(s):  
Imam Syofi'i ◽  
Dendy Adanta ◽  
Aji Putro Prakoso ◽  
Dewi Puspita Sari
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Rural Areas ◽  
Degrees Of Freedom ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Turbulence Models ◽  
Rng Turbulence Model ◽  
Dynamics Method

Crisis electricity was a crucial issue in the rural area. Crossflow turbine (CFT) in pico in pico scale is the best option for electricity provider for rural areas. Due to its usefulness and development of computer technology, computational fluid dynamics method application for CFT study becomes increasingly frequent. This paper compiles the implementation of the computational fluid dynamic (CFD) approach for CFT on a pico scale. Based on the literature, the Renormalization Group (RNG)  turbulence model is recommended to predict the flow field that occurs in CFT because its error is lower than others turbulence models, the RNG  error of 3.08%, standard  of 3.19%, and transitional SST of 3.10%. Furthermore, six-degrees of freedom (6-DoF) is recommended because it has an error of 3.1% than a moving mesh of 9.5% for the unsteady approach. Thus, based on the review, the RNG  turbulence model and 6-DoF are recommended for the CFT on the pico scale.

scholarly journals Performance comparison of a structured bed reactor with and without a chimney tray on the gas-flow maldistribution: A computational fluid dynamics study

2019 ◽  
Vol 234 (1) ◽  
pp. 83-97
Author(s):  
Hajer Troudi ◽  
Moncef Ghiss ◽  
Mohamed Ellejmi ◽  
Zoubeir Tourki
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Gas Flow ◽  
Orientation Angle ◽  
Turbulence Models ◽  
Axial Direction ◽  
Packed Bed ◽  
Performance Comparison ◽  
Maximum Pressure

In the present paper, two configurations of structured reactors (with and without) chimney tray placed below the packed bed have been investigated to study their effect on maldistribution factor and pressure drop characteristics. A simulation result based on a three-dimensional computational fluid dynamics was involved using ANSYS Fluent. First, maldistribution factors without chimney tray were calculated and compared to the results taken from the literature. The results were found to be in good agreement with the experimental data of Yuan et al. Second, the reactor with a chimney tray was modeled in Fluent, and steady-state simulations were performed. The uniformity due to the turbulence of the fluid was carried out using different turbulence models, and the velocity profiles along the axial direction inside the reactor were obtained. As a result, the comparison shows that the presence of a chimney tray yields lower maldistribution factor enhancement by 23% compared to the conventional structured reactor under the same operating condition. The effect of the plate orientation is also determined, and it is found that the maximum pressure drop is achieved through the rows with an orientation angle of α = 45° up to 2.3% higher than of α = 0° and α = 90°.

Analysis of an Airfoil Using a Transition and Turbulence Model

2016 ◽  
Vol 819 ◽  
pp. 356-360
Author(s):  
Mazharul Islam ◽  
Jiří Fürst ◽  
David Wood ◽  
Farid Nasir Ani
Keyword(s):  
Fluid Dynamics ◽  
Boundary Layer ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Turbulence Model ◽  
Original Version ◽  
Transitional Region ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd

In order to evaluate the performance of airfoils with computational fluid dynamics (CFD) tools, modelling of transitional region in the boundary layer is very critical. Currently, there are several classes of transition-based turbulence model which are based on different methods. Among these, the k-kL- ω, which is a three equation turbulence model, is one of the prominent ones which is based on the concept of laminar kinetic energy. This model is phenomenological and has several advantageous features. Over the years, different researchers have attempted to modify the original version which was proposed by Walter and Cokljat in 2008 to enrich the modelling capability. In this article, a modified form of k-kL-ω transitional turbulence model has been used with the help of OpenFOAM for an investigative CFD analysis of a NACA 4-digit airfoil at range of angles of attack.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

scholarly journals Validasi Model Turbulensi pada Simulasi Numerik Menggunakan Software Fluent dengan Sayap Onera M6

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Sulistiya Sulistiya ◽  
Alief Sadlie Kasman
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computational Result ◽  
Computational Simulation ◽  
Turbulence Models ◽  
Wind Tunnels ◽  
Direct Testing ◽  
The World ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

AbstractNumerical simulation using Computational Fluid Dynamics (CFD) method is one way of predicting airflow characteristics on the model. This method is widely used because it is relatively inexpensive and faster in getting desired results compared with performing direct testing. The correctness of a computational simulation output is highly dependent on the input and how it was processed. In this paper, simulation is done on Onera M6 Wing, to investigate the effect of a turbulence model’s application on the accuracy of the computational result. The choice of Onera M6 Wing as a simulation’s model is due to its extensive database of testing results from various wind tunnels in the world. Among Turbulence models used are Spalart-Allmaras, K-Epsilon, K-Omega, and SST.Keywords: CFD, fluent, Model, Turbulence, Onera M6, Spalart-Allmaras, K-Epsilon, K-Omega, SST.AbstraksSimulasi numerik dengan menggunakan metode Computational Fluid Dynamics (CFD) merupakan salah satu cara untuk memprediksi karakteristik suatu aliran udara yang terjadi pada model. Metode ini banyak digunakan karena sifatnya yang relatif murah dan cepat untuk mendapatkan hasil dibandingkan dengan melakukan pengujian langsung. Benar tidak hasil sebuah simulasi komputasi sangat tergantung pada inputan yang diberikan serta cara memproses data inputan tersebut. Pada tulisan ini dilakukan simulasi dengan menggunakan sayap onera M6 dengan tujuan untuk mengetahui pengaruh penggunaan model turbulensi terhadap keakuratan hasil komputasi. Pilihan sayap onera M6 sebagai model simulasi dikarenakan model tersebut sudah memiliki database hasil pengujian yang cukup lengkap dan sudah divalidasi dari berbagai terowongan angin di dunia. Model turbulensi yang digunakan diantaranya Spalart-Allmaras, K-Epsilon, K-Omega dan SST.Kata Kunci : CFD, fluent, Model, Turbulensi, Onera M6, Spalart-Allmaras, K-Epsilon, K-Omega, SST.

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