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Despite the successful use of the Standard − model in simulating turbulent flow for many industrially relevant flows, the model is still less accurate for a range of important problems, such as unconfined flows, curved boundary layers, rotating flows, and recirculating flows. As part of the authors' effort to extend the model applicability and reli...
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... Richardson extrapolation (RE) method is used to predict the discretization error. RE method has been used to select the optimum mesh in CFD-FOM [39]. The equation are as follows [40] (30) r is mesh refinement factor. ...
Computational fluid dynamics (CFD) is extensively utilized to predict flow behaviour in various industries and applications. The Full Order Model (FOM) is a high-accuracy approach to flow modelling, but it requires significant computational resources due to its high order and thousands of variables. To address this problem, the Reduced Order Model (ROM) was developed. Despite the advancement brought by ROM, there is a notable gap in research concerning the impact of mesh configuration on CFD-ROM results. While the number of modes has been extensively studied for its influence on CFD-ROM, the mesh configuration, a critical aspect of the simulation process, has received relatively limited attention. This study investigates the effect of mesh resolution on numerical results in CFD-ROM concerning turbulent flow within stationary parallel plates. Employing rigorous methods, including Richardson Extrapolation, verification, validation, and error percentage. The results explicitly confirm that mesh resolution directly impacts the numerical results of the velocity field in CFD-ROM. It is found that there is a notable reduction in Convergence Grid Index (CGI) values for different mesh ratios: 6.401% for medium-to-coarse and 2.031% for fine-to-medium ratio. Thus, with the same mode number, mesh resolution selection can enhance the numerical result of the velocity field in CFD-ROM.
... The numerical method considered a transient, incompressible turbulent flow by means of the k-ε turbulent model of the Navier-Stokes equations expressed as follows [15][16][17][18][19][20][21]: Continuity equation (1) Momentum equation (2) Energy equation (3) and k-ε equation ...
The major effects of cylindrical and spherical trenched cooling holes with distance between the hole surface and the combustion chamber panel and the filler diameter on the spherical hole contact surface and the panel surface H=0.3,R=D/2=0.1, H=0.3, R=D/2=0.2 and H=0.3, R=D/2=0.3 cm at BR=3.18 on the film cooling effectiveness near the combustor end wall surface is an important subject to study in details. In this research, a three-dimensional representation of a Pratt and Whitney gas turbine engine was simulated and analysed with a commercial finite volume package FLUENT 6.2.26. The analyses were done with RANS turbulence model on internal cooling passages. The combustor simulator was combined with the interaction of two rows of dilution jets, which were staggered in the streamwise direction and aligned in the spanwise direction. In comparison with the baseline case, the application of trenched holes increased the effectiveness of film cooling up to 47% near the wall surface and an average of 35% in depth of combustor simulator .
... Optimasi inverse-prandtl disipasi pada model turbulensi k-ε standar untuk medan aliran air pada turbin cross flow. Nilai konstanta =0,47 dan k=1 direkomendasikan untuk mendapatkan nilai simpangan yang kecil [14]. ...
The provision of food, energy supply, and the provision of information are The food provision, energy supply, and information delivery are controlled to improve people's welfare. In 2011, the national electricity production by PLN was 11% new and renewable energy. 6% hydropower and 5% geothermal. PLN plans the geothermal to be 13% and hydropower to be 6%. The availability of independent PhPP has been built by many communities. PhPP with a waterwheel drive provides a capacity of about 100 watts thus it is only enough for home lighting, whereas the hydro energy potential of the area is quite abundant. The development that has been carried out has several weaknesses; PhPP plump turbine type requires a high head which becomes a constraint for agricultural irrigation, in the other hand PhPP waterwheel type has low efficiency. The research was conducted to develop PhPP low head cross-flow turbine type, which is more efficient. The development begins with the experiment of the PhPP cross-flow turbine model to optimize the ratio of the diameter and width of the runner. A preliminary case study provides experimental results for a cross-flow turbine's torque and power parameters at a flow rate of 0.053 m3/s. Changes in the turbine diameter and width ratio are optimum at a runner width of 10 cm.
... However, only the drag force was considered in this study because the other forces contribute minimally to interphase interactions [24][25][26]. The standard k-turbulence model was adopted to predict turbulent flow behavior [24,27,28]. The governing equations are presented as follows below. ...
Stirred tanks are prevalent in various industries, including chemical, biochemical, and pharmaceutical industries. These reactors are suitable for ensuring efficient massand heat transfer because adequate mixing can be achieved. Numerous studies have been conducted on small-scale stirred-tank reactors. However, upscaling such reactors is challenging because of the complex flow behavior inside the system, especially for the mixing of immiscible liquid–liquid systems. Thus, the objectives of this study were to examine the flow behavior and upscale an immiscible liquid–liquid stirred tank using CFD simulation by investigating a flat-bottomed stirred tank reactor, equipped with a six-blade Rushton turbine. The simulated results were in good agreement with those obtained experimentally. The scale of the reactor significantly affects the hydrodynamic behavior, and the uniformity of the radial distribution of the velocity decreases with increasing Reynolds number. Furthermore, the upscaling criteria were evaluated for geometric similarity and equal mixing times. The proposed scaling law reliably scaled up the immiscible liquid–liquid mixing in a stirred tank with a difference in the range of ±10%.
