Thermals in extremely viscous fluids, including the effects of temperature-dependent viscosity

1986 ◽  
Vol 166 (-1) ◽  
pp. 115 ◽  
Author(s):  
R. W. Griffiths
Keyword(s):  
Viscous Fluids ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Effects Of Temperature ◽  
Dependent Viscosity

An Exact Solution for the Flow of Temperature-Dependent Viscous Fluids in Heated Rectangular Ducts

1973 ◽  
Vol 95 (4) ◽  
pp. 555-557 ◽  
Author(s):  
H. W. Butler ◽  
D. E. McKee
Keyword(s):  
Exact Solution ◽  
Viscous Fluids ◽  
Width Ratio ◽  
Temperature Ratio ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Fully Developed Flow ◽  
Isothermal Case ◽  
Dependent Viscosity ◽  
Viscosity Dependence

An exact solution has been developed for the fully-developed flow of fluids having temperature-dependent viscosity and thermal conductivity in rectangular ducts with transverse heat conduction. The problem is uniquely defined in terms of four parameters: the height-to-width ratio, E, the product of the friction factor and the Reynold’s number, f·Re, the temperature ratio across the duct, T2/T1, and the exponent of the viscosity dependence on temperature. The results indicate that significant departures from the isothermal case may obtain for heated flows.

Entrance and Temperature Dependent Viscosity Effects on Laminar Forced Convection in Straight Ducts With Uniform Wall Heat Flux

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Stefano Del Giudice ◽  
Stefano Savino ◽  
Carlo Nonino
Keyword(s):  
Heat Flux ◽  
Nusselt Number ◽  
Cross Sections ◽  
Local Nusselt Number ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Effects Of Temperature ◽  
Dependent Viscosity ◽  
Fanning Friction Factor ◽  
Laminar Forced Convection

Abstract In this paper a parametric investigation is carried out on the effects of temperature dependent viscosity in simultaneously, i.e., hydro-dynamically and thermally, developing laminar flows of liquids in straight ducts of constant cross sections. Uniform heat flux boundary conditions are imposed on the heated walls of the ducts. Different cross-sectional geometries are considered, corresponding to both axisymmetric (circular and concentric annular) and three-dimensional (rectangular and trapezoidal) ducts. Viscosity is assumed to vary with temperature according to an exponential relation, while the other fluid properties are held constant. A finite element procedure is employed for the solution of the parabolized momentum and energy equations. Computed axial distributions of the local Nusselt number and of the apparent Fanning friction factor are presented for different values of the Pearson and Prandtl numbers. Numerical results confirm that, in the laminar forced convection in the entrance region of straight ducts, the effects of temperature dependent viscosity cannot be neglected in a wide range of operative conditions. Correlations are also provided for the local Nusselt number and the apparent Fanning friction factor in simultaneously developing flows in ducts of different cross sections.

Sign in / Sign up

Export Citation Format

Share Document