Numerical Simulation of Lid-Driven Flows in a Hemispherical Cavity

• Main Authors: LIU,CHIH-WEI, 劉志偉
• Other Authors: LIAO,CING-BIAO
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/9c8n5c

碩士 === 逢甲大學 === 水利工程與資源保育學系 === 105 === This thesis proposes a three-dimensional numerical model in the Cartesian coordinates system, by using the finite difference method to simulate the hemispherical cavity flow. The main difficulty is how to treat the solid boundary in orthogonal grid system. The simplified immersed boundary method and volume of solid method are applied to overcome the irregular solid boundary, and then it is not necessary to use the grid generation technique to deal with issues of complex flow field with solid interface. The numerical model to solve the three-dimensional Navier-Stokes equations is established to investigate the flow regimes in several different Reynolds number. The projection method is first employed to obtain the pressure Poisson equation such that the continuity equation can be satisfied. The pressure is solved directly by using fast Fourier transform method. The velocity can be solved then from the momentum equations by using the Adams-Bashforth scheme, and the virtual force of solid can be obtained to meet the solid boundary condition finally. The numerical flow visualization was carried out from the Tecplot 3D software. The effect of Reynolds number to the flow regimes is investigated. The preliminary results show that the critical Reynolds number is of 2450 in hemispherical cavity flow. The steady state solution can be obtained below this value of Reynolds number. The flow is shown as periodic or non-periodic unsteady solution while the Reynolds number greater than 2450.