Turbulence modulation by variable density and viscosity

We investigate the effectiveness of the semi-local Reynolds number Re τ to parametrize wall-bounded flows with strong density, ρ, and viscosity, µ, gradients. Several cases are considered, namely, volumetrically heated low-Mach-number turbulent channel flows, a simultaneously heated and cooled flow with CO2 at supercritical pressure, and heated and...

Fully compressible low-Mach number simulations of carbon-dioxide at supercritical pressures and trans-critical temperatures

This work investigates fully developed turbulent flows of carbon-dioxide close to its vapour-liquid critical point in a channel with a hot and a cold wall. Two direct numerical simulations are performed at low Mach numbers, with the trans-critical transition near the channel centre and the cold wall, respectively. An additional simulation...

Semi-local scaling and turbulence modulation in variable property turbulent channel flows

We theoretically and numerically investigate the effect of temperature dependent density and viscosity on turbulence in channel flows. First, a mathematical framework is developed to support the validity of the semi-local scaling as proposed based on heuristic arguments by Huang, Coleman, and Bradshaw [“Compressible turbulent channel flows: DNS...

Transient energy growth modulation by temperature dependent transport properties in a stratified plane Poiseuille flow

We investigate the effect of temperature dependent thermal conductivity ? and isobaric specific heat c_P on the transient amplification of perturbations in a thermally stratified laminar plane Poiseuille flow. It is shown that for decreasing thermal conductivity the maximum transient energy growth is amplified with respect to the ?=1 case, while...

Effect of viscosity and density gradients on turbulent channel flows

We perform Direct Numerical Simulations (DNS) of a turbulent channel flow with temperature dependent density and viscosity. The Navier-Stokes equations are solved using their low Mach number formulation. In the simulations performed, the fluid is internally heated and the temperature at the walls is fixed. The friction Reynolds number based on...

Numerical simulation of turbulent heat transfer close to the critical point

In this paper we discuss the effect of sharp property variations on the turbulent heat transfer in fluids close the critical point. The governing equations for this flow regime are discussed, a short description of the numerical tools that have been developed to study these flows is given. Finally, some results for supercritical heat transfer in...

Direct numerical simulation of turbulent flow with supercritical fluid in a heated pipe

This work investigates turbulent heat transfer to a pipe flow with a fluid close to its vapour-liquid critical point. The flow is simulated using Direct Numerical Simulations (DNS) of the anelastic Navier-Stokes equations at a Reynolds number of Ret = 360, based on the friction velocity ut at the inlet and the diameter of the pipe. Turbulent...