Jun Cao's research while affiliated with Ryerson University and other places

Publications (24)

Article
In this paper, the original finite volume lattice Boltzmann method (FVLBM) on an unstructured grid (Part I of these twin papers) is extended to simulate turbulent flows. To model the turbulent effect, the k−ω SST turbulence model is incorporated into the present FVLBM framework and is also solved by the finite volume method. Based on the eddy visco...
Article
In this paper, an unstructured grid based finite volume lattice Boltzmann method (FVLBM) that can be used for the simulation of incompressible laminar flows is presented and studied in detail. This method is derived from a simple modification of the cell-vertex unstructured grid based FVLBM proposed by Stiebler et al. (2006). Compared with other co...
Preprint
In this paper, the finite volume lattice Boltzmann method (FVLBM) on unstructured grid presented in Part I of this paper is extended to simulate the turbulent flows. To model the turbulent effect, the $k-\omega$ SST turbulence model is incorporated into the present FVLBM framework and also is solved by the finite volume method. Based on the eddy vi...
Preprint
Full-text available
In this paper, a finite volume lattice Boltzmann method (FVLBM) based on cell-center unstructured girds is presented and full studied to simulate the incompressible laminar flows, which is simple modified from the cell-vertex unstructured girds FVLBM proposed by Stiebler et al. [Computers & Fluids, 2006, 35(8): 814-819]. Compared with other complex...
Article
A tornado is fundamentally a devastating airflow featuring simultaneous translation and rotation. This hybrid nature makes the simulations more interesting as well as challenging. Numerous laboratorial and computational simulations of tornadoes have been performed in the past few decades to study the tornado dynamics. This study concentrates on the...
Article
A tornadic wind is essentially considered as an airflow that simultaneously translates and rotates. Numerical simulations of this kind of hybrid flow remain inadequate due to many numerical difficulties, one of the major challenges consisting in the establishment of a set of boundary conditions that are, for the tornado-obstacle interaction scenari...
Conference Paper
A numerical analysis of complex and coupled processes such as heat and mass transports, reaction kinetics, charge transport and flow has been attempted in this study to develop the performance of the PEM fuel cell. An improved 2-dimentioanl proton exchange membrane (PEM) fuel cell model including two finite-thickness catalysts and a fully hydrated...
Article
Flame acceleration and deflagration-to-detonation transition (DDT) are investigated in a 24m long and 80mm by 80mm square cross section steel duct with arrayed obstacles. Blockage ratio and spacing are varied to determine their effect on flame acceleration. The experiments were conducted with stoichiometric coal gas-air mixture, and the effect of m...
Article
Robust use of adaptive mesh refinement (AMR) techniques in the immersed-boundary (IB) lattice Boltzmann method (LBM) framework is seldom reported, but indeed expected owing to its foreseeable broad applicability and computational efficiency. This study is aimed at developing a highly hybrid computational framework that seamlessly incorporates the A...
Article
This study focuses on developing an adaptive finite difference method oriented by the a posteriori error estimator that is originally derived from the finite element analysis, building a novel type of hybrid mesh adaptive technique that has not been reported elsewhere as of today. The time-dependent heat conduction problem is chosen for numerical i...
Article
Full-text available
This paper seeks to make a systematic study over the complex four-lid-driven cavity flows using the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). The flow is generated by moving the top wall to the right and the bottom wall to the left, while moving the left wall downwards and the right wall upwards, with an identical moving speed....
Article
This paper seeks to make a systematic study over a series of lid-driven flow in various deep cavities using the filter-matrix lattice Boltzmann (FMLB) model. A concise description of the FMLB model is presented in this paper, and important numerical considerations for effective use of the FMLB model are also clearly elucidated. In particular, the s...
Article
Following the first part of this study, the filter-matrix lattice Boltzmann (FMLB) model is now applied to the investigation of the bifurcation behavior in the lid-driven deep-cavity flow. In this second part, the first Hopf bifurcations in the lid-driven cavity flow patterns with aspect ratios of 1–5 are examined in detail, revealing that the crit...
Article
Full-text available
As a fundamental subject in fluid mechanics, sophisticated cavity flow patterns due to the movement of multi-lids have been routinely analyzed by the computational fluid dynamics community. Unlike those reported computational studies that were conducted using more conventional numerical methods, this paper features employing the multiple-relaxation...
Article
A mathematical model for the proton exchange membrane fuel cell (PEMFC) is developed in this study. The model features assessing the thermodiffusion effect on the PEM fuel cell performance, which has been conventionally neglected in existing fuel cell modeling studies. Also, instead of treating catalyst layers simply as interfaces, the model assign...
Article
This paper presents a lattice Boltzmann method (LBM) based study aimed at numerical simulation of highly turbulent and largely inclined flow around obstacles of curved geometry using non-body-fitted Cartesian meshes. The approach features (1) combining the interpolated bounce-back scheme with the LBM of multi-relaxation-time (MRT) type to enable th...
Article
Full-text available
In this study, a new filter-matrix lattice Boltzmann (FMLB) model is proposed and extended to include incompressible thermal flows. A new equilibrium solution is found in the improved FMLB model, which is derived from the Hermite expansion. As a result, the velocity-dependent pressure is removed, which is an inherent defect of Somers's FMLB model....
Article
In order to solve compressible turbulent flow problems, this study focuses on incorporating the Spalart–Allmaras turbulence model into gas-kinetic BGK (Bhatnagar–Gross–Krook) scheme. The Spalart–Allmaras turbulence model is solved using finite difference discretization. The variables on the cell interface are interpolated via the van Leer limiter i...
Article
Full-text available
The main goal of this paper is to develop the coupled double- distributionfunction (DDF) lattice Boltzmann method (LBM) for simulation of subsonic and transonic turbulent flows. In the present study, we adopt the second-order implicit-explicit (IMEX) Runge-Kutta schemes for time discretization and theNon-Oscillatory andNon- Free-Parameters Dissipat...
Article
An increasing amount of attention has been paid on the study of thermodiffusion effects on mass transport. This paper presents a novel mathematical model for an entire proton exchange membrane fuel cell (PEMFC) with focus placed on the modeling and assessment of the role of thermodiffusion that has been usually neglected in previous fuel cell resea...

Citations

... For the nearly incompressible flows with complex boundaries, the authors in [21] developed a second-order accurate finite volume LBM by which the fluxes were computed in one step, whereas the previous method calculated over two steps. Wang et al. studied steady and unsteady flows on unstructured grids using the cell-center finite volume formulation and LBM, and performed incompressible laminar flow [22] and turbulent flow simulations [23]. ...
... More uniform heat distribution and elimination of hot zones in the cavity is observed by increasing porosity and reducing Richardson number." LBM was used and adapted to investigate double-diffusive convection in fluid-saturated porous media in [35] and for arbitrary combinations of solid, fluid, and porous media in [36]. Both models are in good agreement with their validation cases and are therefore proposed for their respective problems [35,36]. ...
... The papers included in this special issue are all related to two kinetic methods: the lattice Boltzmann equation (LBE) [1-11] and the gas-kinetic scheme (GKS) [12]. These papers are about the numerical analysis of the LBE [1-4] and its implementations [5], and modeling and simulation of a wide rangine flows including suspensions [6], fluid-fluid interface [7,8], bio-fluid [9], fluid-structure interaction [10], aerodynamics of tornado-like wind [11], and turbulent flow [12]. ...
... To overcome that tedious updating process, Guo et.al. [8][9] re-formulated the RCVM to model the two-dimensional (2D) tornado-building interaction with the aid of immersed boundary (IB) method and the "relative motion" principle, resulting in a "virtual" scenario in which the building "moves" at a velocity that is the negative of the translation velocity of the tornado, while the background airflow has only a rotational component about its "pinned" center. Thus, as long as the computational domain is large enough for its outer boundary to little affected by the inner flow evolution induced by the "virtual translation" of the building, the time-dependency and, hence, the kinematic condition updating process, can be effectively eliminated at the outer boundary of the computational domain. ...
... A general detailed non-isothermal, two-dimensional CFD model including two finite-thickness catalysts is presented by Yin and Cao (2009). Another general detailed novel mathematical model for an entire PEM fuel cell is developed by Jaralla et al. (2010Jaralla et al. ( , 2013 with focus placed on the modelling and assessment of the role of thermodiffusion that has been neglected in previous fuel cell research work. Built upon the aforementioned studies, a new PEM fuel cell model is developed in this paper. ...
... The indirect initiation of detonations refers to a category that the reactive mixture can be ignited by a weak energy source, Communicated by N. Smirnov. B J. Li jian_li@bit.edu.cn 1 which is usually followed by a deflagration-to-detonation transition process (DDT) [1][2][3][4][5][6]. The direct initiation of detonations [7][8][9][10][11][12] is that the detonation is formed instantaneously via rapidly depositing a large amount of energy in an extremely small volume. ...
... 8 Guo et al. applied AMR to the immersed boundary LBM and bubble function in interpolation. 9 These methods extend the LBM to more universal cases. However, the numerical time step is still restricted by particle relaxation time. ...
... Similarly, Wahba [5] and Perumal et al. [6] presented multiple solutions of square cavity flow driven by two non-facing walls. Moreover, Zhuo et al. [7], Wahba [5] and Perumal et al. [6] presented multiple solutions of square cavity flow driven by four side walls. These studies are examples for flow problems with square cavity geometry that has multiple solutions. ...
... It was clear that, if A is decreased further, the number of main eddies increases from 4 to 6 via a similar eddy genesis mechanism. Zhuo et al. 47 studied numerically the complex four-lid-driven cavity°ows using the multiple-relaxation-time (MRT) lattice Boltzmann method. The MRT-LBM results reveal a lot of important features of bifurcated°ow. ...
... Zhen-Hua, Bao-Chang, and Lin [4] have simulated flow in a liddriven cavity by Multiple-Relaxation-Time Lattice Boltzmann Method (MRT-LBM) for higher values of Reynolds numbers (20,000 ≤ Re ≤ 100, 000), and this study is the first attempt to simulate 2D cavity flow for a maximum of Re = 100, 000. Using MRT-LBM, fluid flow inside the two lid-driven cavities has been investigated by Guo et al. [5]. Du and Liu [6] have investigated natural convection in a side-heated cavity using MRT-LBM to simulate fluid flow and SRT-LBM to simulate the temperature field. ...