Abstract In this study, the stability dependence of turbulent Prandtl number ( $$Pr_t$$ P r t ) is quantified via a novel and simple analytical approach. Based on variance flux budget equations, hybrid length scale formulation fir...

Simulations of turbulent convection flow adjacent to a two-dimensional backward-facing step are presented to explore the effects of step height on turbulent separated flow and heat transfer. Reynolds number and duct’s height downstream from the step are kept constant at Re0 = 28,000 and H = 0.19 m, respectively. Uniform and constant heat flux of qw = 270 W/m 2 is specified at the stepped wall d...

High resolution computer simulations of two-dimensional convection using the anelastic approximation are presented. These calculations span Rayleigh numbers from 10(8)-10(12) for Prandtl number equal to unity, with the fluid density decreasing by a factor of 12 from the bottom to the top of the convection region. This range covers several decades in the "hard" turbulent regime. While many studi...

High resolution computer simulations of two-dimensional convection using the anelastic approximation are presented. These calculations span Rayleigh numbers from 10 10 for Prandtl number equal to unity, with the uid density decreasing by a factor of 12 from the bottom to the top of the convection region. This range covers several decades in the \hard" turbulent regime. While many studies of thi...

Measurements of the Nusselt number Nu and of a Reynolds number Re(eff) for Rayleigh-Bénard convection (RBC) over the Rayleigh-number range 10(12)≲Ra≲10(15) and for Prandtl numbers Pr near 0.8 are presented. The aspect ratio Γ≡D/L of a cylindrical sample was 0.50. For Ra≲10(13) the data yielded Nu∝Ra(γ(eff)) with γ(eff)≃0.31 and Re(eff)∝Ra(ζ(eff)) with ζ(eff)≃0.43, consistent with classical turb...

The origin of strong magnetic fields in the Universe can be explained by amplifying weak seed fields via turbulent motions on small spatial scales and subsequently transporting the magnetic energy to larger scales. This process is known as the turbulent dynamo and depends on the properties of turbulence, i.e., on the hydrodynamical Reynolds number and the compressibility of the gas, and on the ...

A direct numerical simulation of a turbulent channel flow with three passive scalars at different molecular Prandtl numbers is performed. Computed statistics including the turbulent Prandtl numbers are compared with existing experimental data. The computed fields are also examined to investigate the spatial structure of the scalar fields. The scalar fields are highly correlated with the streamw...

Transitional flow, whereby the motion of a fluid changes from laminar to turbulent flow, was successfully identified by Reynolds (1883) almost 130 years ago. According to ASHRAE (2009), for a round pipe, in general, laminar flow exists when the Reynolds number is less than 2 300. Fully turbulent flow exists when the Reynolds number is larger than 10 000 and transitional flow exists for Reynolds...