Impact of temperature dependent diffusion coefficients on heat and mass transport in viscoelastic liquid using generalized Fourier theory

This article considers the behavior of diffusion coefficients (varying with respect to the fluid temperature) by using Cattaneo–Christov (generalized Fourier) models based on the first law of thermodynamics and conservation of diffusion of specie. Mathematical models are developed and the finite element method is used for computational purposes. The computer programme is tested and validated. An excellent agreement between published results is observed. The results obtained from numerical experiments are displayed graphically and the numerical values of momentum, temperature and concentration gradients versus emerging physical parameters are tabulated. The elasticity of the fluid is responsible for restoration of the deformation of viscoelastic liquid for the cases of constant viscosity and temperature dependent viscosity. The rate of diffusion of wall momentum slows down as the elasticity of the fluid (through the Deborah number) is increased. The qualitative and quantitative behavior of constant diffusion coefficients are noted. The diffusion of momentum in viscoelastic liquid is compared to the viscoelastic liquid of diffusion coefficients. As an increase in the ratio of momentum diffusion to thermal diffusion reduces the rate of diffusion of momentum of wall into the viscoelastic liquid, it is noted that wall temperature diffuses into viscoelastic liquid of constant viscosity faster than the diffusion of wall temperature into viscoelastic liquid of temperature dependent diffusion coefficients. It is also observed that concentration of specie in viscoelastic liquid of constant viscosity is less than the concentration in liquid of temperature dependent viscosity. (paper)