A ghost-cell immersed boundary method for the simulations of heat transfer in compressible flows under different boundary conditions Part-II: Complex geometries

Two methods for solid body representation in flow simulations available in the Pencil Code are the immersed boundary method and overset grids. These methods are quite different in terms of computational cost, flexibility and numerical accuracy. We present here an investigation of the use of the different methods with the purpose of assessing their strengths and weaknesses. At present, the overset grid method in the Pencil Code can only be used for representing cylinders in the flow. For this task it surpasses the immersed boundary method in yielding highly accurate solutions at moderate computational costs. This is partly due to local grid stretching and a body-conformal grid, and partly due to the possibility of working with local time step restrictions on different grids. The immersed boundary method makes up the lack of computational efficiency with flexibility in regards to application to complex geometries, due to a recent extension of the method that allows our implementation of it to represent arbitrarily shaped objects in the flow.

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“…7(a). The treatment of some special cases that may occur during this process is described in Luo et al (2017).…”

Section: Complex Geometriesmentioning

confidence: 99%

“…Here, we adopt a method based on the robust procedure proposed in Mittal et al (2008). For details, see Luo et al (2017).…”

Section: Complex Geometriesmentioning

confidence: 99%

Treatment of solid objects in the Pencil Code using an immersed boundary method and overset grids

Aarnes

Jin

Mao

et al. 2018

Geophysical & Astrophysical Fluid Dynamics

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“…A forcing function/term accompanied by the Navier-Stokes equations is responsible for fluid-solid interactions. A detailed survey on IBM was provided by Mittal and Iaccarino (2005), and its application was reported in Mixing in a constricted micro channel various fluid dynamics problems (Francois et al, 2004;Wang et al, 2007;Saleel et al, 2011;Wang et al, 2009;Ren et al, 2013;Shu et al, 2013;Saleel et al, 2013;He et al, 2015;Luo et al, 2017;Nestola et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on pressure-driven electro osmatic flow and mixing in a constricted micro channel by triangular obstacle

Saleel

Afzal

Badruddin

et al. 2020

HFF

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Purpose The characteristics of fluid motions in micro-channel are strong fluid-wall surface interactions, high surface to volume ratio, extremely low Reynolds number laminar flow, surface roughness and wall surface or zeta potential. Due to zeta potential, an electrical double layer (EDL) is formed in the vicinity of the wall surface, namely, the stern layer (layer of immobile ions) and diffuse layer (layer of mobile ions). Hence, its competent designs demand more efficient micro-scale mixing mechanisms. This paper aims to therefore carry out numerical investigations of electro osmotic flow and mixing in a constricted microchannel by modifying the existing immersed boundary method. Design/methodology/approach The numerical solution of electro-osmotic flow is obtained by linking Navier–Stokes equation with Poisson and Nernst–Planck equation for electric field and transportation of ion, respectively. Fluids with different concentrations enter the microchannel and its mixing along its way is simulated by solving the governing equation specified for the concentration ﬁeld. Both the electro-osmotic effects and channel constriction constitute a hybrid mixing technique, a combination of passive and active methods. In microchannels, the chief factors affecting the mixing efficiency were studied efficiently from results obtained numerically. Findings The results indicate that the mixing efficiency is influenced with a change in zeta potential (ζ), number of triangular obstacles, EDL thickness (λ). Mixing efficiency decreases with an increment in external electric field strength (Ex), Peclet number (Pe) and Reynolds number (Re). Mixing efficiency is increased from 28.2 to 50.2% with an increase in the number of triangular obstacles from 1 to 5. As the value of Re and Pe is decreased, the overall percentage increase in the mixing efficiency is 56.4% for the case of a mixing micro-channel constricted with five triangular obstacles. It is also vivid that as the EDL overlaps in the micro-channel, the mixing efficiency is 52.7% for the given zeta potential, Re and Pe values. The findings of this study may be useful in biomedical, biotechnological, drug delivery applications, cooling of microchips and deoxyribonucleic acid hybridization. Originality/value The process of mixing in microchannels is widely studied due to its application in various microfluidic devices like micro electromechanical systems and lab-on-a-chip devices. Hence, its competent designs demand more efficient micro-scale mixing mechanisms. The present study carries out numerical investigations by modifying the existing immersed boundary method, on pressure-driven electro osmotic flow and mixing in a constricted microchannel using the varied number of triangular obstacles by using a modified immersed boundary method. In microchannels, the theory of EDL combined with pressure-driven flow elucidates the electro-osmotic flow.

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“…In our previous work, a ghost‐cell compressible IB method of second‐order accuracy is designed to enforce Dirichlet, Neumann, and Robin type thermal boundary conditions. And an extension to complex phase‐interface is made by Luo et al But until now, there are few studies about the immersed boundary method involving multiphase chemical reactions. McGurn et al investigated the conjugate heat‐transfer and mass‐transfer processes associated with charring solids.…”

Section: Introductionmentioning

confidence: 99%

Fully resolved simulations of single char particle combustion using a ghost‐cell immersed boundary method

et al. 2018

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A novel ghost‐cell immersed boundary method for fully resolved simulation of char particle combustion has been developed. The boundary conditions at the solid particle surface, such as velocity, temperature, density, and chemical species concentration, are well enforced through the present method. Two semiglobal heterogeneous reactions and one homogeneous reaction are used to describe the chemical reactions in the domain, and the Stefan flow caused by the heterogeneous reactions is considered. A satisfactory agreement can be found between the present simulation results and experimental data in the literature. The method is then used to investigate the combustion property of a char particle and the interaction between CO2 gasification and O2 oxidation. Furthermore, combustion effect on the exchange of mass, momentum and energy between gas‐ and solid‐ phase is explored. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2851–2863, 2018

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A ghost-cell immersed boundary method for the simulations of heat transfer in compressible flows under different boundary conditions Part-II: Complex geometries

Cited by 35 publications

References 47 publications

Treatment of solid objects in the Pencil Code using an immersed boundary method and overset grids

Treatment of solid objects in the Pencil Code using an immersed boundary method and overset grids

Numerical investigation on pressure-driven electro osmatic flow and mixing in a constricted micro channel by triangular obstacle

Fully resolved simulations of single char particle combustion using a ghost‐cell immersed boundary method

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