Decomposition of the wall-heat flux of compressible boundary layers

Assessment of inflow boundary conditions for compressible turbulent boundary layers

A description of different inflow methodologies for turbulent boundary layers, including validity and limitations, is presented. We show that the use of genuine periodic boundary conditions, in which no alteration of the governing equations is made, results in growing mean flow and decaying turbulence. Premises under which the usage is valid are presented and explained, and comparisons with the...

Boundary Layers for the Navier-Stokes Equations of Compressible Heat-Conducting Flows with Cylindrical Symmetry

We consider the Navier-Stokes equations for viscous compressible heat-conducting fluids with cylindrical symmetry. Our main purpose is to study the boundary layer effect and convergence rates as the shear viscosity μ goes to zero. We show that the boundary layer thickness and a convergence rate are of order O(μ) with 0 < α < 1/2 and O( √ μ) respectively, thus extending the result for isentropic...

Estimating the unknown heat flux on the wall of a heat exchanger internal tube using inverse method

In the design of heat exchangers, it is necessary to determine the heat transfer rate between hot and cold fluids in order to calculate the overall heat transfer coefficient and the heat exchanger efficiency. Heat transfer rate can be determined by inverse methods. In this study, the unknown space-time dependent heat flux imposed on the wall of a heat exchanger internal tube is estimated by app...

Thermal boundary layers and heat flux in turbulent convection: The role of recirculating flows.

A numerical study of compressible turbulent boundary layers

Compressible turbulent boundary layers with free-stream Mach number ranging from 2.5 up to 20 are analyzed by means of direct numerical simulation of the Navier–Stokes equations. The fluid is assumed to be an ideal gas with constant specific heats. The simulation generates its inflow condition using the rescaling-recycling method. The main objective is to study the effect of Mach number on turb...