Effect Of Fluid Type Research Articles

Generation of the Karman Vortex Street at Low Reynolds Number due to Cooling of a Cylinder. Cause and Fluid Type Effect.

For clarification of the cause and effect of fluid type on the generation of the Karman vortex street due to cooling of a cylinder at a low Reynolds number where the Karman vortex street does not occur in an isothermal wake, the two-dimensional, laminar, time-dependent continuity equation, Navier-Stokes equations with the buoyant term of Boussinesq's approximation, and energy equation are solved numerically for a circular cylinder wake with an upward freestream of mercury, air, and water. The cause is the generation of the wake vorticity which does not occur in an isothermal wake, and a stable arrangement of vorticity. With a decrease in the Prandtl number of the fluid, the Karman vortex street is generated easily by cooling of a cylinder, and has lower frequency, lower velocity of the vortex movement, and larger scale of vortex spiral than the isothermal Karman vortex.