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On the Semi-Analytical Solution of Displacement Thickness in a Laminar Streamwise Corner Flow Assisted by Computational Fluid Dynamics Simulation
(2023-01-01)
Bumrungthaichaichan, Eakarach
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Unaprom, Prajaree
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Sathianchok, Pakapong
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Wattananusorn, Santi
In this paper, the new semi-analytical correlation for displacement thickness of laminar fluid flow along an arbitrary-angle corner formed by the intersection of two plates has been proposed because of the discrepancy in displacement thickness for strong interference corner between the present computational fluid dynamics simulation and previous analytical correlation.
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CFD Simulations of High Efficiency Gas Cyclones: An Influence of Dustbin Geometry
(2021-01-01)
Pechmanee, Pitiwat
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Namkanisorn, Apinan
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Wattananusorn, Santi
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Bumrungthaichaichan, Eakarach
The unsteady state simulation of gas-solid cyclone separator was carried out to investigate the performances of 0.29 m diameter (D<inf>B</inf>) cyclones with five different dustbin geometries, including dustbin without dipleg (cylindrical bin) and dustbins with 0.5D<inf>B</inf>, 1.0D<inf>B</inf>, 1.5D<inf>B</inf>, and 2.0D<inf>B</inf> (divergent conical bin) height divergent conical diplegs. The diameter and total height of five dustbins were 1D<inf>B</inf> and 2D<inf>B</inf>, respectively. The gas flow and turbulence fields inside the cyclones with the Reynolds number of 280,000 were simulated by Reynolds averaged Navier-Stokes equations (RANS) with Reynolds stress model (RSM). The collection efficiencies were investigated by using discrete phase model (DPM). For model validation, the simulated velocity profiles of the cyclone with cylindrical dustbin have been compared to the previous experimental data available in literature and were in good agreement with the previous results. Further, the simulated results revealed that the Stairmand cyclone with divergent conical and simple cylindrical dustbins respectively represented the highest and lowest collection efficiencies indicated by 50% cut-off diameter, which corresponded to the diameters of 1.692 and 1.744 microns, respectively.
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CFD modelling of pump-around jet mixing tanks: a reliable model for overall mixing time prediction
(2019-07-04)
Bumrungthaichaichan, Eakarach
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Wattananusorn, Santi
Over the past two decades or so, computational fluid dynamics (CFD) has been employed to predict overall mixing times inside jet mixing tanks instead of non-universal mixing time correlations obtained by experiments. However, the numerical methods for jet mixing tank simulations were not clearly tested and the discretization errors of the previous CFD models were not assessed. So, in this paper, the suitable turbulence model and numerical methods for pump-around jet mixing tank simulations were investigated. Further, the discretization errors of the present CFD models were estimated with the help of grid convergence index (GCI). The results revealed that the realizable k-epsilon model, SIMPLE, second order upwind, and first order implicit were proper turbulence model and numerical methods for pump-around jet mixing tank simulations. From GCI analyses, the maximum discretization uncertainty in overall mixing time of the present CFD models was about ±0.08 s.
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CFD modelling of pump-around jet mixing tanks: a discrepancy in concentration profiles
(2018-10-03)
Bumrungthaichaichan, Eakarach
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Namkanisorn, Apinan
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Wattananusorn, Santi
Jet mixing tanks are important in chemical processes. Over the past two decades or so, computational fluid dynamics (CFD) has been employed to study jet mixers. The shortfalls of the previous CFD models were the discrepancy in concentration profiles between simulation and experiment and the absence of exact inlet turbulence conditions. So, in our present work, the CFD model was developed to investigate the proper conditions for jet mixing tank simulation and improve the accuracy of concentration profile prediction by using an appropriate grid arrangement, a realizable k-epsilon model, and a second-order upwind discretization scheme. The results revealed that the CFD model with proper inlet conditions predicted the overall mixing time well and somewhat improved the predicted concentration profiles. Further, the reasons for discrepancies in concentration profiles were inappropriate inlet turbulence conditions and overprediction in total momentum available for mixing due to the flat top liquid surface assumption. In addition, this discrepancy may be caused by the dynamic response of concentration measuring device.
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A review on numerical consideration for computational fluid dynamics modeling of jet mixing tanks
(2016-11-01)
Bumrungthaichaichan, Eakarach
Over two decades or so, the computational fluid dynamics (CFD) modeling of various jet mixing tank configurations was developed and published. Further, the studies of various parameters used in experimental and CFD works were also reviewed to obtain the optimal design procedure. However, the numerical setup for jet mixing tank modeling was not studied and reported. Hence, in this review paper, the important numerical setup for CFD simulation of jet mixing tanks, including numerical solution techniques, turbulence model selection, boundary conditions, numerical methods, solution strategy, and CFD grid, are clearly demonstrated to achieve the comprehensive CFD modeling guideline for jet mixing tank. Further, the validations for jet mixing tank models are also represented.
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Investigation of entrance length in circular and noncircular conduits by computational fluid dynamics simulation
(2014-01-01)
Tongpun, Pimpun
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Bumrungthaichaichan, Eakarach
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Wattananusorn, Santi
This study estimated entrance length of circular and noncircular conduits, including circle, triangle, square and hexagon cross-sectional conduit, by using computational fluid dynamics (CFD). For simulation condition, the length of non-circular conduit was 10 m and the hydraulic diameter was 0.2 m. The laminar flow with Reynolds number of 500 and turbulent flow with Reynolds number of 50,000 were applied to investigate water flow in conduits. The governing equations were solved iteratively by using ANSYS FLUENT 14.0. For turbulent flow simulation, standard k-epsilon and RNG k-epsilon model were employed to simulate turbulence. The preliminary results were validated by comparison with theoretical data. At first, grid independency was evaluated to optimize the model. Norm* was employed to investigate the entrance length, which is related to velocity. The simulated results revealed that the entrance length for laminar flow was longer than turbulent flow.

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