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Krishnendu Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.

  • thermal boundary layer in stagnation point flow past a permeable shrinking sheet with variable surface temperature
    Propulsion and Power Research, 2017
    Co-Authors: Md Sharif Uddin, Krishnendu Bhattacharyya
    Abstract:

    Abstract An investigation is made to study the heat transfer in boundary layer stagnation-point flow over a non-isothermal permeable shrinking sheet with suction/injection. In this study, Power-Law variation of sheet temperature is considered. By similarity transformation, the governing equations with the boundary conditions are transformed to self-similar nonlinear ordinary differential equations and then those are solved numerically by shooting method. In presence of variable sheet temperature, the variation of temperature is analysed. For larger shrinking rate compared to that of straining rate, dual solutions for velocity and temperature are obtained. It is found that for positive value of Power-Law Exponent of variable sheet temperature heat transfer at the sheet as well as heat absorption at the sheet with temperature overshoot near the sheet occur and for negative value heat transfer from the sheet occurs though there is overshoot away from the sheet. With increasing positive Power-Law Exponent heat transfer reduces for first solution and heat absorption enhances for second solution. Whereas, with increasing magnitude of negative Power-Law Exponent heat transfer increases for second solution and for first solution the heat transfer increases for larger shrinking rate and it decreases for smaller shrinking rate. Due to suction heat transfer/absorption increases in all cases and for injection heat transfer/absorption increases for first solution and decreases for second solution. Also, interesting effects of suction/injection and Prandtl number on temperature distribution are observed when the sheet temperature varies (directly/inversely) along the sheet.

  • exact solution for thermal boundary layer in casson fluid flow over permeable shrinking sheet with variable wall temperature and thermal radiation
    alexandria engineering journal, 2016
    Co-Authors: Krishnendu Bhattacharyya, Md Sharif Uddin, G C Layek
    Abstract:

    Abstract An analysis of thermal boundary layer in the flow of Casson fluid over a permeable shrinking sheet with variable wall temperature and thermal radiation is made. Using similarity transformations, self-similar nonlinear ODEs are obtained from the governing equations. Dual exact solutions of transformed velocity and energy equations are obtained. From the plotted results it can be observed that the temperature inside the boundary layer decreases with Casson parameter and wall mass transfer parameter in first solution and it increases in second solution. Whereas, temperature decreases for larger values of Prandtl number, radiation parameter and Power-Law Exponent for inverse variation along the sheet in both solutions and it enhances with Power-Law Exponent for direct variation along the surface. Also, thermal boundary layer thickness reduces with stronger thermal radiation and inverse variation of wall temperature along the surface and it becomes thicker with direct variation of wall temperature. The rate of heat transfer is less with increasing values of Power-Law Exponent for direct variation along the sheet and for inverse variation it is higher. In graphical representation of temperature field, temperature overshoot is observed in certain cases. So, in some situations heat absorption at surface occurs instead of heat transfer from surface.

Siegfried Stapf - One of the best experts on this subject based on the ideXlab platform.

  • a simple scaling derivation of the shear thinning Power Law Exponent in entangled polymer melts
    Polymer, 2011
    Co-Authors: N Fatkullin, Carlos Mattea, Siegfried Stapf
    Abstract:

    By suggesting that the polymer dynamics in entangled polymer melts possesses the property of dynamical self-similarity, we argue that the Power-Law Exponent of the Carreau-Yasuda Law, which empirically describes the shear thinning effect of the polymer melt viscosity, is inversely proportional to the Exponent of the molecular mass dependence of the terminal relaxation time. This finding is obtained in cases where the shear rate dependence of the segmental relaxation time is negligible. If such dependence is essential, the Carreau-Yasuda Law is slightly modified at high shear rates: instead of a Power-Law dependence with a small shear rate independent Exponent, a weaker logarithmic dependence is found both for shear rate and molecular mass dependence, which resembles the approach to zero of an effective shear rate and molecular mass dependent Power-Law Exponents at sufficiently high shear rates.

  • a simple scaling derivation of the shear thinning Power Law Exponent in entangled polymer melts
    arXiv: Materials Science, 2010
    Co-Authors: N Fatkullin, Carlos Mattea, Siegfried Stapf
    Abstract:

    This paper has been withdrawn by the author, because it final version is published in: N. Fatkullin, C. Mattea, S. Stapf, Polymer 52 (2011) 3522.

A G Kelessis - One of the best experts on this subject based on the ideXlab platform.

  • a classification scheme for the wind profile Power Law Exponent in terms of the pasquill stability classes
    1992
    Co-Authors: N M Zoumakis, A G Kelessis
    Abstract:

    Semiempirical formulations which have been proposed to describe the surface layer wind and potential temperature profiles, were used to derive relationships between the wind profile Power-Law Exponent, p, the Monin-Obukhov scaling length, L, and the surface roughness parameter, z0. Nomograms were constructed for ξ=z/L, as a function of ξ0=z0/L and p, for stable and unstable conditions.Using Golder’s graph (1972) a classification scheme was obtained for p and ξ in terms of the Pasquill A-F stability classes anywhere in the surface layer. The theoretical analysis indicates that, during stable conditions, p is computed at the height z=(z2−z1)/ln(z2/Z1), instead of the widely used geometric mean height, between top (z2) and bottom (z1) of the layer considered.

  • methodology for bulk approximation of the wind profile Power Law Exponent under stable stratification
    Boundary-Layer Meteorology, 1991
    Co-Authors: N M Zoumakis, A G Kelessis
    Abstract:

    The variation of the wind profile Power-Law Exponent (p) with respect to changes in atmospheric stability is depicted using the formulation of Ku et al. (1987) for specifying the Monin-Obukhov scaling length (L) under stable atmospheric conditions. The theoretical estimates for the bulk approximation of p as a function of L under stable conditions compare well with Power-Law Exponent data from various sources and the theoretical analysis from Irwin (1979).

  • methodology for bulk approximation of the wind profile Power Law Exponent under stable stratification research note
    1991
    Co-Authors: N M Zoumakis, A G Kelessis
    Abstract:

    The variation of the wind profile Power-Law Exponent (p) with respect to changes in atmo- spheric stability is depicted using the formulation of Ku et al. (1987) for specifying the Monin- Obukhov scaling length (L) under stable atmospheric conditions. The theoretical estimates for the bulk approximation of p as a function of L under stable conditions compare well with Power-Law Exponent data from various sources and the theoretical analysis from Irwin (1979).

Satoru Morita - One of the best experts on this subject based on the ideXlab platform.

  • Power Law Exponent in multiplicative langevin equation with temporally correlated noise
    Journal of the Physical Society of Japan, 2018
    Co-Authors: Satoru Morita
    Abstract:

    Power-Law distributions are ubiquitous in nature. Random multiplicative processes are a basic model for the generation of Power-Law distributions. For discrete-time systems, the Power-Law Exponent is known to decrease as the autocorrelation time of the multiplier increases. However, for continuous-time systems, it is not yet clear how the temporal correlation affects the Power-Law behavior. Herein, we analytically investigated a multiplicative Langevin equation with colored noise. We show that the Power-Law Exponent depends on the details of the multiplicative noise, in contrast to the case of discrete-time systems.

  • Power Law Exponent in multiplicative langevin equation with temporally correlated noise
    arXiv: Statistical Mechanics, 2017
    Co-Authors: Satoru Morita
    Abstract:

    Power-Law distributions are ubiquitous in nature. Random multiplicative processes are a basic model for the generation of Power-Law distributions. It is known that, for discrete-time systems, the Power-Law Exponent decreases as the autocorrelation time of the multiplier increases. However, for continuous-time ystems, it has not yet been elucidated as to how the temporal correlation affects the Power-Law behavior. Herein, we have analytically investigated a multiplicative Langevin equation with colored noise. We show that the Power-Law Exponent depends on the details of the multiplicative noise, in contrast to the case of discrete-time systems.

  • Power Law in random multiplicative processes with spatio temporal correlated multipliers
    EPL, 2016
    Co-Authors: Satoru Morita
    Abstract:

    It is well known that random multiplicative processes generate Power-Law probability distributions. We study how the spatio-temporal correlation of the multipliers influences the Power-Law Exponent. We investigate two sources of the time correlation: the local environment and the global environment. In addition, we introduce two simple models through which we analytically and numerically show that the local and global environments yield different trends in the Power-Law Exponent.

G C Layek - One of the best experts on this subject based on the ideXlab platform.

  • exact solution for thermal boundary layer in casson fluid flow over permeable shrinking sheet with variable wall temperature and thermal radiation
    alexandria engineering journal, 2016
    Co-Authors: Krishnendu Bhattacharyya, Md Sharif Uddin, G C Layek
    Abstract:

    Abstract An analysis of thermal boundary layer in the flow of Casson fluid over a permeable shrinking sheet with variable wall temperature and thermal radiation is made. Using similarity transformations, self-similar nonlinear ODEs are obtained from the governing equations. Dual exact solutions of transformed velocity and energy equations are obtained. From the plotted results it can be observed that the temperature inside the boundary layer decreases with Casson parameter and wall mass transfer parameter in first solution and it increases in second solution. Whereas, temperature decreases for larger values of Prandtl number, radiation parameter and Power-Law Exponent for inverse variation along the sheet in both solutions and it enhances with Power-Law Exponent for direct variation along the surface. Also, thermal boundary layer thickness reduces with stronger thermal radiation and inverse variation of wall temperature along the surface and it becomes thicker with direct variation of wall temperature. The rate of heat transfer is less with increasing values of Power-Law Exponent for direct variation along the sheet and for inverse variation it is higher. In graphical representation of temperature field, temperature overshoot is observed in certain cases. So, in some situations heat absorption at surface occurs instead of heat transfer from surface.