MEASUREMENT AND PREDICTION OF NATURAL-CONVECTION VELOCITIES IN TRIANGULAR ENCLOSURES

Free convection velocities were predicted with a finite element method and measured using laser velocimetry in three isosceles triangular en closures with base angles of 30 degrees, 45 degrees, and 60 degrees. T hree Grashof numbers were tested for each geometry, which ranged from 1.89 x 10(6) to 10.3 x 10(6). Velocity data were measured near the two isothermal side walls and the isothermal bottom wall. Data were nondi mensionalized by the same parameters used to nondimensionalize incline d plate data. Flows were laminar for ail cases. For a given base angle , the nondimensional data and predictions collapsed to single curves b est for either of the side walls with typical variations of 5 percent; nondimensional predictions and data collapsed poorly for the bottom w alls, with typical variations of 20 percent. Hot and cold side-wall da ta exhibited similitude and typical differences between nondimensional results for the two side walls were 10 percent. For varying base angl es, side-wall results failed to reduce to single curves with variation s of typically 50 percent. Absolute differences between predicted and measured peak velocities ranged from 6 to 35 percent. Differences betw een predicted and measured velocities for base angles of 30 and 60 deg rees tended to be positive, whereas, differences for a base angle of 4 5 degrees, tended to be negative.