Radiative entropy production

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76465/1/AIAA-9535-710.pd

Numerical investigations of planar solidification of an undercooled liquid

We investigate evolution of a planar interface during unstable solidification of a pure undercooled liquid between two parallel plates. The governing equations are solved using a front tracking/finite difference technique that allows discontinuous material properties between the phases and interfacial anisotropy. The simulations produce some of the futures of the dendritic solidification which are in good qualitative agreement with the works of the previous investigators. The effects of the physical parameters on the crystal growth and interface instability are also examined. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87387/2/629_1.pd

On interface dynamics

An intuitive study is presented for unstable interfacial waves. The maximum wavelength obtained for the most rapid unstable growth is shown to have a universal part which also characterizes the isotropic scales of buoyancy-driven turbulence. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70336/2/PHFLE6-12-5-1244-1.pd

Radiative deformation

An infinitesimal change δQδQ in heat flux Q is shown, in terms of entropy flux Ψ=Q/T,Ψ=Q/T, to have two parts, δQ=TδΨ+ΨδT.δQ=TδΨ+ΨδT. The first part being the thermal displacement and the second part being the thermal deformation. Only the second part dissipates into internal energy and generates entropy. Thermodynamic arguments are extended to transport phenomena. It is shown that the thermal part of the rate of local entropy generation is related to the local rate of thermal deformation by s′′′=−ψi/T(∂T/∂xi),s′′′=−ψi/T(∂T/∂xi), where ψi=qi/T,ψi=qi/T, ψiψi being the rate of entropy flux vector, and qiqi the rate of heat flux vector. The part of this generation related to radiation is illustrated in terms of an example. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70807/2/JAPIAU-87-6-3093-1.pd

Entropy production in boundary layers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77333/1/AIAA-197-774.pd

Local energy balance, specific heats and the Oberbeck-Boussinesq approximation

A thermodynamic argument is proposed in order to discuss the most appropriate form of the local energy balance equation within the Oberbeck-Boussinesq approximation. The study is devoted to establish the correct thermodynamic property to be used in order to express the relationship between the change of internal energy and the temperature change. It is noted that, if the fluid is a perfect gas, this property must be identified with the specific heat at constant volume. If the fluid is a liquid, a definitely reliable approximation identifies this thermodynamic property with the specific heat at constant pressure. No explicit pressure work term must be present in the energy balance. The reasoning is extended to the case of fluid saturated porous media.Comment: 14 pages, 2 figures, 1 table, submitted for publicatio