Natural convection of non-Newtonian fluid along a vertical thin cylinder using modified power-law model

2016 ◽  
Author(s):  
Sharaban Thohura ◽  
Md. Mamun Molla ◽  
M. M. A. Sarker
Keyword(s):  
Natural Convection ◽  
Newtonian Fluid ◽  
Power Law ◽  
Power Law Model ◽  
Thin Cylinder ◽  
Modified Power Law

Non-Newtonian Natural Convection Along a Vertical Heated Wavy Surface Using a Modified Power-Law Viscosity Model

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. M. Molla ◽  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Shear Rate ◽  
Power Law ◽  
Leading Edge ◽  
Numerical Results ◽  
Wavy Surface ◽  
Viscosity Model ◽  
Length Scale ◽  
Modified Power Law

Natural convection of non-Newtonian fluids along a vertical wavy surface with uniform surface temperature has been investigated using a modified power-law viscosity model. An important parameter of the problem is the ratio of the length scale introduced by the power-law and the wavelength of the wavy surface. In this model there are no physically unrealistic limits in the boundary-layer formulation for power-law, non-Newtonian fluids. The governing equations are transformed into parabolic coordinates and the singularity of the leading edge removed; hence, the boundary-layer equations can be solved straightforwardly by marching downstream from the leading edge. Numerical results are presented for the case of shear-thinning as well as shear-thickening fluid in terms of the viscosity, velocity, and temperature distribution, and for important physical properties, namely, the wall shear stress and heat transfer rates in terms of the local skin-friction coefficient and the local Nusselt number, respectively. Also results are presented for the variation in surface amplitude and the ratio of length scale to surface wavelength. The numerical results demonstrate that a Newtonian-like solution for natural convection exists near the leading edge where the shear-rate is not large enough to trigger non-Newtonian effects. After the shear-rate increases beyond a threshold value, non-Newtonian effects start to develop.

Height Extrapolation of Wind Data

1985 ◽  
Vol 107 (1) ◽  
pp. 10-14 ◽  
Author(s):  
A. S. Mikhail
Keyword(s):  
Wind Speed ◽  
Power Law ◽  
Wind Data ◽  
Power Law Model ◽  
Short Term ◽  
Shape Factors ◽  
Wind Speeds ◽  
Average Wind ◽  
Modified Power Law

Various models that are used for height extrapolation of short and long-term averaged wind speeds are discussed. Hourly averaged data from three tall meteorological towers (the NOAA Erie Tower in Colorado, the Battelle Goodnoe Hills Tower in Washington, and the WKY-TV Tower in Oklahoma), together with data from 17 candidate sites (selected for possible installation of large WECS), were used to analyze the variability of short-term average wind shear with atmospheric and surface parameters and the variability of the long-term Weibull distribution parameter with height. The exponents of a power-law model, fit to the wind speed profiles at the three meteorological towers, showed the same variability with anemometer level wind speed, stability, and surface roughness as the similarity law model. Of the four models representing short-term wind data extrapolation with height (1/7 power law, logarithmic law, power law, and modified power law), the modified power law gives the minimum rms for all candidate sites for short-term average wind speeds and the mean cube of the speed. The modified power-law model was also able to predict the upper-level scale factor for the WKY-TV and Goodnoe Hills Tower data with greater accuracy. All models were not successful in extrapolation of the Weibull shape factors.

scholarly journals Numerical Simulation of Drop Formation in Power-Law Fluids

2018 ◽  
Vol 34 (6) ◽  
pp. 3153-3156
Author(s):  
Fahime Hoseinzade ◽  
Hamid Reza Ghorbani
Keyword(s):  
Newtonian Fluid ◽  
Power Law ◽  
Drop Size ◽  
Two Dimensions ◽  
Orifice Diameter ◽  
Fluid Flow Rate ◽  
Power Law Model ◽  
Motion Equations ◽  
Power Law Fluids ◽  
Submerged Orifice

The purpose of this work was the study of the formation process of Newtonian drop in a continuous non-Newtonian fluid. This process was numerically studied by entering liquid into a submerged orifice in a cylindrical vessel. The simulations were carried out using SOLA-VOF method. In this code, the complete motion equations were predicted two dimensions and using finite difference method. In addition, power law model was used to simulate a non-Newtonian fluid. In this research, the effects of orifice diameter and Newtonian fluid flow rate were studied on the formation of the drop, size and its formation time.

Non-Newtonian Natural Convection Along a Vertical Flat Plate With Uniform Surface Temperature

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
S. Ghosh Moulic ◽  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Shear Rate ◽  
Newtonian Fluid ◽  
Power Law ◽  
Similarity Solution ◽  
Leading Edge ◽  
Boundary Layer Equations ◽  
Shear Thinning Fluid ◽  
Vertical Flat Plate

Natural-convection boundary-layer flow of a non-Newtonian fluid along a heated semi-infinite vertical flat plate with uniform surface temperature has been investigated using a four-parameter modified power-law viscosity model. In this model, there are no physically unrealistic limits of zero or infinite viscosity that are encountered in the boundary-layer formulation for two-parameter Ostwald–de Waele power-law fluids. The leading-edge singularity is removed using a coordinate transformation. The boundary-layer equations are solved by an implicit finite-difference marching technique. Numerical results are presented for the case of a shear-thinning fluid. The results indicate that a similarity solution exists locally in a region near the leading edge of the plate, where the shear rate is not large enough to induce non-Newtonian effects; this similarity solution is identical to the similarity solution for a Newtonian fluid. The size of this region depends on the Prandtl number. Downstream of this region, the solution of the boundary-layer equations is nonsimilar. As the shear rate increases beyond a threshold value, the viscosity of the shear-thinning fluid is reduced. This leads to a decrease in the wall shear stress compared with that for a Newtonian fluid. The reduction in the viscosity accelerates the fluid in the region close to the wall, resulting in an increase in the local heat transfer rate compared with the case of a Newtonian fluid.

Non-Newtonian Lubrication Theory for Rough Surfaces: Application to Rigid and Elastic Rollers

1982 ◽  
Vol 24 (3) ◽  
pp. 147-154 ◽  
Author(s):  
P. Sinha ◽  
J. B. Shukla ◽  
C. Singh ◽  
K. R. Prasad
Keyword(s):  
Surface Roughness ◽  
Elastic Deformation ◽  
Newtonian Fluid ◽  
Power Law ◽  
Reynolds Equation ◽  
Stochastic Theory ◽  
Power Law Model ◽  
Pure Rolling ◽  
Lubrication Characteristics ◽  
Rigid Surfaces

To predict the consequences of the interaction of the lubricant rheology with surface roughness, the stochastic theory of lubrication for Newtonian fluid is modified to take into account the non-Newtonian behaviour of the lubricant, by considering the power law model. Generalized forms of the Reynolds equation for two types of roughness arrangements, viz., longitudinal and transverse, are derived. These equations are subsequently used to study the lubrication characteristics of infinitely long rough roller bearings, and two particular cases, namely pure rolling (rigid surfaces) and rolling with elastic deformation, are discussed.

scholarly journals Viscosity and dispersion effects on natural convection from a vertical cone in a nonnewtonian fluid saturated porous medium

2011 ◽  
Vol 15 (suppl. 2) ◽  
pp. 307-316 ◽  
Author(s):  
Rishi Kairi
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Newtonian Fluid ◽  
Power Law ◽  
Ambient Medium ◽  
Concentration Field ◽  
Physical Parameters ◽  
Vertical Cone

This paper investigates the influence of double dispersion and viscosity on natural convection heat and mass transfer from vertical cone in a non-Darcy porous medium saturated with non- Newtonian fluid. The surface of the cone and the ambient medium are maintained at constant but different levels of temperature and concentration. The Ostwald-de Waele power law model is used to characterize the non-Newtonian fluid behavior. A similarity solution for the transformed governing equations is obtained. The numerical computation is carried out for various values of the non-dimensional physical parameters. The effect of non-Darcy parameter, viscosity parameter, thermal and solutal dispersion, buoyancy ratio, Lewis number and power-law index parameter on the temperature and concentration field as well as on the heat and mass transfer coefficients is analyzed.

Sign in / Sign up

Export Citation Format

Share Document