Zoran Žunič

Natural convection flows in complex cavities by BEM

A numerical method for the solution of the Navier‐Stokes equations is developed using an integral representation of the conservation equations. The velocity‐vorticity formulation is employed, where the kinematics is given with the Poisson equation for a velocity vector, while the kinetics is represented with the vorticity transport equation. The corresponding boundary‐domain integral equations are presented along with discussions of the kinetics and kinematics of the fluid flow problem. The boundary‐domain integral formulation is developed and tested for natural convection flows in closed cavities with complex geometries.

Computational Study of Heat Transfer in Honeycomb Structures Accounting for Gaseous Pore Filler

Thermal properties of honeycomb structures with different cell shapes are investigated in this paper. The influence of cell shape, relative density and pore gases on the macroscopic honeycomb thermal properties is investigated by means of transient dynamic computational simulations. The ANSYS CFX code is used to evaluate the heat conduction trough the base material and the filler gas, as well as the convection in gas filler. The computational results clearly show a strong influence of the filler gas on heat conduction and macroscopic thermal properties of analyzed honeycomb structures, which is attributed to low relative density of the cellular structure. Additionally, the influence of considered relative densities is more prominent than the influence of cell shape. The evaluated results are valuable for further development of homogenization models of heat transfer in honeycomb structures accounting for gaseous pore fillers.

Solution of 3D Velocity‐Vorticity Formulation of the Navier‐Stokes Equations by Boundary Element Method

A novel algorithm for the simulation of laminar viscous flows by solving of 3D velocity‐vorticity formulation of the Navier‐Stokes equations is presented. The algorithm employs a combination of a subdomain boundary element method (BEM) and single domain BEM. The subdomain BEM is used to solve the kinematics and vorticity transport equations. We use continuous quadratic interpolation of function and discontinuous linear interpolation of flux. The resulting over‐determined system of linear equations is solved in a least squares manner. The single domain BEM is employed to calculate boundary vorticity values, which are used as Dirichlet boundary conditions for the vorticity transport equation. The versatility and accuracy of the proposed algorithm is proven by simulating 3D channel flow and 3D lid driven cavity flows up to Re = 103.