Convective heat transfer in airflow through a duct with wall thermal radiation

This paper presents a numerical investigation on airflow through a heated horizontal rectangular duct wherein the model considers the combined modes of natural and forced convection heat transfer and the thermal radiation from duct walls. The duct periphery is differentially heated with known temperature profiles imposed on the two opposite vertical sidewalls while the other two walls are treated as adiabatic. The air enters into the duct hydrodynamically fully developed and flows steadily under laminar conditions undergoing thermal development within the duct. Considering several temperature profiles on the two vertical sidewalls, the numerical simulation generates the heat transfer rates and associated fluid flow patterns in the duct for a range of airflow rates, duct aspect ratios and surface emissivity. The variation of local Nusselt number at duct walls and the fluid flow patterns are critically examined to identify thermal instabilities and the significance of wall thermal radiation effects on the overall heat transfer rates

Analysis of low Reynolds number flow around a heated circular cylinder

The objective of this study is to investigate the forced convection from and the flow around a heated cylinder. Experimental and computational results are presented for laminar flow around a heated circular cylinder with a diameter of 10 mm. The experiments were carried out using Particle Image Velocimetry (PIV) in a wind tunnel, and numerical simulations using an in-house code and a commercial software package, FLUENT. This paper pre-sents comparisons for vorticity and temperature contours in the wake of the cylinder. Experimental and computa-tional results are compared with those available in the literature for heated and unheated cylinders. An equation is suggested for a temperature-dependent coefficient defining a reference temperature to be used in place of the con-stant used in other studies. An attempt is also made to correct differences between average cylinder surface tem-perature and measured interior temperature of the cylinder

Chaos for the Hyperbolic Bioheat Equation

The Hyperbolic Heat Transfer Equation describes heat processes in which extremely short periods of time or extreme temperature gradients are involved. It is already known that there are solutions of this equation which exhibit a chaotic behaviour, in the sense of Devaney, on certain spaces of analytic functions with certain growth control. We show that this chaotic behaviour still appears when we add a source term to this equation, i.e. in the Hyperbolic Bioheat Equation. These results can also be applied for the Wave Equation and for a higher order version of the Hyperbolic Bioheat Equation.The authors are supported in part by MEC and FEDER, Projects MTM2010-14909 and MTM2013-47093-P.Conejero, JA.; Ródenas Escribá, FDA.; Trujillo Guillen, M. (2015). Chaos for the Hyperbolic Bioheat Equation. Discrete and Continuous Dynamical Systems - Series A. 35(2):653-668. doi:10.3934/dcds.2015.35.653S65366835