LATTICE BOLTZMANN METHOD SIMULATION ON FLOW PATTERNS OF NATURAL CONVECTION IN HORIZONTAL CYLINDRICAL ANNULUS

摘要

The Lattice Boltzmann method is used to simulate the flow patterns of natural convection in horizontal cylindrical annulus for aspect ratios in the range of 0.4≤A≤10 and for Prandtl numbers varying from 0.1 to 0.7. At Pr=0.3 and A=2, flow patterns on the whole range of Rayleigh number are mapped indicating the lower and upper critical values for transitions. At Pr=0.7, the influence of aspect ratio on flow pattern is analyzed acquiring the result that the oscillation flow never happens at A≤3. At A=2, several Prandtl numbers are calculated at certain Rayleigh number and the conclusion is that the steady upward flow keeps when 0.5≤Pr. The results are found in good agreement with existed studies.