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.

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 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

scholarly journals HISTORY OF UTILIZATION OF THE COMPUTATIONAL FLUID DYNAMICS METHOD FOR STUDY PICO HYDRO TYPE CROSS-FLOW

2021 ◽  
Vol 2 (1) ◽  
pp. 017-024
Author(s):  
Dendy Adanta ◽  
Dewi Puspita Sari ◽  
Nura Muaz Muhammad ◽  
Aji Putro Prakoso
Keyword(s):  
Relative Error ◽  
Turbulence Model ◽  
Rural Areas ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Electrical Power ◽  
Cross Flow ◽  
Moving Mesh ◽  
Absolute Relative Error ◽  
The Absolute

Energy crisis in particular, electricity in the isolated rural areas of Indonesia is a very crucial issue that needs to be resolve through  electrification . Compared to other options, pico hydro cross-flow turbine (CFT) is the better option to provides electrical power for the isolated rural areas. Studies to improve CFT performance can be undertaken analytically, numerically, experimentally, or a combination of those methods. However, the development of computer technology makes numerical simulation studies have become increasingly frequent. This paper describes the utilization of the computational fluid dynamic (CFD) approach in the pico hydro CFT method. This review has resulted that the recommended Renormalization Group (RNG) k-ε turbulence model for CFT CFD simulation because its absolute relative error is lower than standard k-ε and transitional Shear Stress Transport (SST). The absolute relative error for the RNG k-ε turbulence model of 3.08%, standard k-ε of 3.19%, and transitional SST of 3.10%. While for the unsteady approach, the six-degrees of freedom (6-DoF) are considered because more accurate than moving mesh. The absolute relative error for 6-DoF of 3.1% and moving mesh of 9.5%. Thus, based on the review, the RNG k-ε turbulence model and 6-DoF are proposed for the pico hydro CFT CFD study.

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.

Vortex Induced Vibration of Circular Cylinder With Two Degrees of Freedom: Computational Fluid Dynamics vs. Reduced-Order Models

2013 ◽  
Author(s):  
Enhao Wang ◽  
Qing Xiao ◽  
Narakorn Srinil ◽  
Hossein Zanganeh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Circular Cylinder ◽  
Degrees Of Freedom ◽  
Cross Flow ◽  
Reduced Order Models ◽  
Two Dimensional ◽  
Two Degrees Of Freedom ◽  
Reduced Order ◽  
Dual Resonance

Computational fluid dynamics (CFD) studies capturing vortex-induced vibration (VIV) phenomena in a wide range of both the hydrodynamics and the structural parameters are important, because the analysis outcomes can be applied to numerical prediction codes, complement experimental measurement results and suggest a modification of some practical design guidelines. Nevertheless, in spite of many published studies on VIV, CFD studies for two dimensional coupled cross-flow/in-line VIV even with two degrees of freedom (2-DoF), are still quite limited. More CFD studies which can control the equivalence of system fluid-structure parameters in different directions with reduced uncertainty are needed to improve the numerical model empirical coefficients and capability to effectively match numerical predictions and experimental outcomes. This paper presents a CFD study on the 2-DoF VIV of elastically mounted circular cylinder with a low mass ratio (m* = 2.55). The Reynolds number is fixed to be 150 and the reduced flow velocity parameter is varied by changing the cross-flow natural frequency. To model the problem, two-dimensional Navier-Stokes equations coupled with linear structural equations in the in-line and cross-flow directions are solved. Particular attention is paid to the determination of maximum attainable amplitudes and the associated instantaneous lift and drag forces and hydrodynamic coefficients. These results are compared with the obtained results from alternative numerical prediction outcomes using new reduced-order models with four nonlinearly coupled wake-structure oscillators (Srinil and Zanganeh, 2012). Some qualitative and quantitative aspects are discussed. Overall, the important VIV characteristics are captured including the dual-resonance and figure-of-eight trajectories. Through the flow visualization study, it is found that as the dual-resonance is excited, a P+S wake pattern appears.

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.

FLUCTUACIONES INDUCIDAS DEL FLUJO DE AIRE EN UN DUCTO CON PAREDES DENTADAS

2020 ◽  
Vol 24 (105) ◽  
pp. 63-71
Author(s):  
San Luis B. Tolentino Masgo ◽  
Juan Toledo Hernández
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shock Waves ◽  
Materials Science ◽  
Turbulence Modeling ◽  
Dynamic Instability ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Ansys Fluent ◽  
Fluids Mechanics

Estudios experimentales y numéricos han centrado el interés en el campo de flujo con superficies de paredes dentadas y cavidades, donde la turbulencia del flujo son captadas en imágenes con la técnica Schlieren y recreadas con códigos computacionales. En el presente trabajo, se realiza un estudio numérico para el flujo de aire en un ducto recto con paredes dentadas para seis casos de presión. El flujo se simuló para un dominio computacional 2D con el código ANSYS-Fluent, para lo cual se empleó el modelo RANS en conjunto con el modelo de turbulencia de Menter. Se obtuvieron los campos de número de Mach, velocidad, presión y temperatura con presencia de remolinos y ondas de choque. En ciertas regiones el flujo presentó desviaciones al chocar con las esquinas de los dientes, por lo cual originó fluctuaciones inducidas de los parámetros termodinámicos aguas abajo y hacia la región del centro; en los espacios entre dientes se presentó remolinos; al final del último diente se presentó ondas de choque oblicuas. Se concluye que la sección dentada incrementa la turbulencia e influye a que la velocidad del flujo tenga un incremento escalonado en régimen transónico. Palabras Clave: ducto, flujo de aire, fluctuación, onda de choque, pared dentada, simulación. Referencias [1]J. Blazek, Computational fluid dynamics: principles and applications. Butterworth- Heinemann, 2015. [2]B. Andersson, R. Andersson, L. Håkansson, M. Mortensen, R. Sudiyo, B. van Wachem, y L. Hellström, Computational Fluid Dynamics Engineers. Cambridge University Press, 2012. [3]T. V. Karman, “The fundamentals of the statistical theory of turbulence,” Journal of the Aeronautical Sciences, vol. 4, no. 4, pp. 131–138, 1937. doi: 10.2514/8.350. [4]F. White, Viscous fluid flow. McGraw-Hill Education, 2005. [5]H. Schlichting, Boundary-layer theory. McGraw-Hill classic textbook reissue series, 2016. [6]J. D. Anderson, Fundamentals of aerodynamics. McGraw-Hill series in aeronautical and aerospace engineering, 2017. [7]D. C. Wilcox, Turbulence modeling for CFD. DCW Industries, 2006. [8]P. Krehl y S. Engemann, “August toepler — the first who visualized shock waves,” Shock Waves, vol. 5, no. 1, pp. 1–18, Jun 1995. doi: 10.1007/BF02425031. [9]G. S. Settles, “Toma ultrarrápida de imágenes de ondas de choque, explosiones y disparos,” Revista Investigación y Ciencia, pp. 74-83, May. 2006. https://www.investigacionyciencia.es [10]H. Hirahara, M. Kawahashi, M. U, Khan y K. Hourigan, “Experimental investigation of fluid dynamic instability in a transonic cavity flow,” Experimental Thermal and Fluid Science, 31, pp. 333–347, 2007. doi: 10.1016/j.expthermflusci.2006.05.007. [11]S. L. Tolentino, S. Caraballo, J. Toledo, J. Mírez y C. Torres, “Oscilaciones de la velocidad del flujo en un ducto recto con cavidades rectangulares,” XVI Jornadas de Investigación 2018, UNEXPO Puerto Ordaz, Venezuela, pp. 34-39, 2018. [12]S. Jeyakumar, K. A. Yuvaraj, K. Jayaraman, F. Cardona y M. T. Sultan, “Effect of cavity fore wall modifications in supersonic flow,” Conference, Materials Science and Engineering, 152, pp. 1-7, 2016. doi: 10.1088/1757-899X/152/1/012002. [13]S. L. Tolentino and S. Caraballo, “Estudio del flujo de aire en un conducto recto con pared dentada,” XIV Jornadas de Investigación 2016, UNEXPO Puerto Ordaz, Venezuela, pp. 203-210, 2016. [14]F. White, Fluids Mechanics. McGraw-Hill Education, 2016. [15]F. R. Menter, “Two equation eddy-viscosity turbulence models for engineering applications,” AIAA Journal, vol. 32, no. 8, pp. 1598-1605, 1994. doi: 10.2514/3.12149. [16]S. L. B. Tolentino Masgo, “Evaluación de modelos de turbulencia para el flujo de aire en una tobera plana,” Revista Ingenius, no. 22, pp. 25-37, Julio-Diciembre 2019. doi: 10.17163/ings.n22.2019.03. [17]S. L. B. Tolentino Masgo, “Evaluación de modelos de turbulencia para el flujo de aire en un difusor transónico,” Revista Politécnica, vol. 45, no. 1, pp. 25-38, 2020. doi: 10.3333/rp.vol45n1.03.

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.

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