Polyhedral meshing as an innovative approach to computational domain discretization of a cyclone in a fluidized bed CLC unit

Abstract

Abstract. Chemical Looping Combustion (CLC) is a technology that allows the separation of CO2, which is generated by the combustion of fossil fuels. The majority of process designs currently under investigation are systems of coupled fluidized beds. Advances in the development of power generation system using CLC cannot be introduced without using numerical modelling as a research tool. The primary and critical activity in numerical modelling is the computational domain discretization. It influences the numerical diffusion as well as convergence of the model and therefore the overall accuracy of the obtained results. Hence an innovative approach of computational domain discretization using polyhedral (POLY) mesh is proposed in the paper. This method reduces both the numerical diffusion of the mesh as well as the time cost of preparing the model for subsequent calculation. The major advantage of POLY mesh is that each individual cell has many neighbours, so gradients can be much better approximated in comparison to commonly-used tetrahedral (TET) mesh. POLYs are also less sensitive to stretching than TETs which results in better numerical stability of the model. Therefore detailed comparison of numerical modelling results concerning subsection of CLC system using tetrahedral and polyhedral mesh is covered in the paper.

The influence of distance between vehicles in platoon on aerodynamic parameters

“…Additional face sizing on surfaces representing car models was defined as 5mm with 1.1 growth rate in order to refine the mesh in the vicinity of the analysed Ahmed bodies. Such meshing procedure was previously validated in [13]. The above mentioned meshing settings resulted in the final mesh consisting of approx.…”

Numerical Analysis of Flow in Building Arrangement: Computational Domain Discretization

“…Apart from the selection and parameterization of a turbulence model, the discretization of the computational domain is a particularly important task in the case of flow modelling in built-up areas because it influences the CPU time, as well as the accuracy of the results [16][17][18]. Therefore an innovative approach to discretization method of the analysed domain representing the array of two buildings located in an urban environment is addressed in the carried out research.…”

“…In some cases, POLY can even achieve better accuracy than HEX due to larger numbers of neighbouring elements allowing for an interchange of mass over a larger number of faces, reducing numerical diffusion effects caused by flows not perpendicular to any of the cell faces. This proves to be advantageous in situations where no prevailing flow direction can be identified and leads to a more accurate solution achieved with a lower cell count [17,29].…”

The influence of computational domain discretization on CFD results concerning aerodynamics of a vehicle

“…On the other hand, TETRA cells cannot be stretched excessively, so a significantly larger number of elements has to be used in order to properly represent the investigated geometry. POLY elements are worth investigating as their numerical diffusion is at a level comparable to HEX and in addition, POLYs can easily by applied to describe even very complicated geometries [13]. The individual POLY element neighbors with more cells in comparison to HEX and TETRA, which improves the calculation of llows better heat and mass transfer through numerous faces.…”

“…Computational Fluid Dynamics (CFD) is one of such methods and its application as a research tool is common in various industries including automotive [5] and [6], civil-engineering [7][8][9][10][11], power engineering [12,13] and others [14]. CFD allows for low-cost product design and/or improvement.…”