Thermal radiation on unsteady electrical MHD flow of nanofluid over stretching sheet with chemical reaction

This paper focuses on the effects of suction as well as thermal radiation, chemical reaction, viscous dissipation and Joule heating on a two-dimensional natural convective flow of unsteady electrical magnetohydrodynamics (MHD) nanofluid over a linearly permeable stretching sheet. One significant aspect of this study is that electric field employed in revised Buongiorno model has been introduced in view of enhancement of thermal conductivity and consequently better convective heat transfer. The constitute governing equations have been converted into strong non-linear ordinary differential equations by employing suitable transformations and these transformed equations are solved by the Implicit finite difference. From this study, it is found that the presence of magnetic field and suction slows down the fluid motion while it enhances for higher values of an electric field which tends to firmness sticky effect. It is also found that enhancing thermal radiation leads to an increase in nanofluid temperature. The Nusselt number increases with both Brownian motion and unsteadiness parameters

Towards a solution of the closure problem for convective atmospheric boundary-layer turbulence

We consider the closure problem for turbulence in the dry convective atmospheric boundary layer (CBL). Transport in the CBL is carried by small scale eddies near the surface and large plumes in the well mixed middle part up to the inversion that separates the CBL from the stably stratified air above. An analytically tractable model based on a multivariate Delta-PDF approach is developed. It is an extension of the model of Gryanik and Hartmann [1] (GH02) that additionally includes a term for background turbulence. Thus an exact solution is derived and all higher order moments (HOMs) are explained by second order moments, correlation coefficients and the skewness. The solution provides a proof of the extended universality hypothesis of GH02 which is the refinement of the Millionshchikov hypothesis (quasi- normality of FOM). This refined hypothesis states that CBL turbulence can be considered as result of a linear interpolation between the Gaussian and the very skewed turbulence regimes. Although the extended universality hypothesis was confirmed by results of field measurements, LES and DNS simulations (see e.g. [2-4]), several questions remained unexplained. These are now answered by the new model including the reasons of the universality of the functional form of the HOMs, the significant scatter of the values of the coefficients and the source of the magic of the linear interpolation. Finally, the closures 61 predicted by the model are tested against measurements and LES data. Some of the other issues of CBL turbulence, e.g. familiar kurtosis-skewness relationships and relation of area coverage parameters of plumes (so called filling factors) with HOM will be discussed also

Prediction of thermal and energy transport of MHD Sutterby hybrid nanofluid flow with activation energy using Group Method of Data Handling (GMDH)

The present research work pursues GMDH for predicting thermal and energy transport of 2-D radiative magnetohydrodynamic (MHD) flow of hybrid Sutterby nanofluid across a moving wedge with activation energy. An exclusive class of nanoparticles SWCNT-Fe(3)O(4 )and MWCNT-Fe3O4 are dispersed into the ethylene glycol as regular fluid. The hybrid nanofluid mathematical model has been written as a system of partial differential equations (PDEs), which are then converted into ordinary differential equations (ODEs) through similarity replacements. Numerical solutions are attained Runge-Kutta-Fehlberg's fourth fifth-order (RKF-45) scheme by adopting the shooting technique. The ranges of diverse sundry parameters used in our study are Hartree parameter 0.1 <= m <= 0.5, magnetic parameter 0.3 <= M <= 1, Deborah number 0.1 <= De <= 1, moving wedge parameter 0.3 <= gamma <= 0.9, Reynolds number 0 <= Re <= 2.5, solid volume fraction of Fe3O4 and CNTs0.005 <= phi(1) <= 0.1,0.005 <= phi(2) <= 0.06, Browanian motion 0.1 <= Nb <= 0.4, thermophoresis parameter 0.1 <= Nt <= 0.25, Eckeret number 0.05 <= Ec <= 1, radiation parameter 1 <= R-d <= 2.5, Lewis number 0.5 <= Le <= 1.5, chemical reaction rate 0.1 <= sigma <= 0.7, heat source parameter, 0 <= delta <= 1.5 and activation energy 1 <= E <= 4 which shows up during the speed, thermal, and focus for Fe3O4/C2H6O2 nanofluid and CNTs-Fe3O4/C2H6O2 hybrid nanofluid. Additionally, the friction coefficient (C-fx), rate of heat transport (H-tx), and rate of nanoparticle transport (Nt(x) are calculated using GMDH. The numerical results for the current analysis are illustrated via tables, graphs, and contour plots. The efficiency of the proposed GMDH models is assessed using statistical measures such as MSE, MAE, RMSE, R, Error mean and Error StD. The predicted values are very close to the numerical results, and the coefficient of determination R-2 of C-fx,N-tx, and H-tx are 1, 0.97836 and 0.9960, respectively, which shows the best settlement

Analysis of Thermal Radiation and Ohmic Heating Effects on the Entropy Generation of MHD Williamson Fluid through an Inclined Channel

In this present work, the heat irreversibility analysis of thermal radiation, Ohmic heating, and angle of inclination on Williamson fluid is presented. The developed equations are converted to dimensionless forms, and Homotopy perturbation method (HPM) is used to solve the resulting coupled ordinary differential equations. The heat irreversibility analysis is achieved by substituting the obtained results into entropy generation and Bejan number expressions. The HPM solution for the velocity profile is validated by comparing it with a previously published study in some limited cases, and an excellent agreement is established. Fluid motion is accelerated by the increasing values of thermal radiation parameter, whereas the magnetic parameter and Reynolds number reduce it. Furthermore, except for the Weissenberg and Prandtl numbers, all of the flow parameters examined enhance fluid temperature. In addition, entropy generation is enhanced at the channel's upper wall for all parameters except magnetic field parameter

Stirring and mixing : 1999 Program of Summer Study in Geophysical Fluid Dynamics

The central theme of the 1999 GFD Program was the stirring, transport, reaction and mixing of passive and active tracers in turbulent, stratified, rotating fluids. The problem of mixing in fluids has applications in areas ranging from oceanography to engineering and astrophysics. In geophysical settings, mixing spans and unites a broad range of scales -- from micrometers to megameters. The mixing of passive tracers is of fundamental importance in environmental and industrial problems, such as pollution, and in determining the large-scale heat and salt balance of the worlds oceans. The transport of active tracers, on the other hand, such as vorticity, plays a key role in the turbulence that occurs in most geophysical and astrophysical fluids. William R. Young (Scripps Institution of Oceanography) gave a series of principal lectures, the notes of which as taken by the fellows, appear in this volume. Report of the projects of the student fellows makes up the second half of this volume.Funding was provided by the National Science Foundation under Grant No. OCE-9810647 and the Office of Naval Research under Grant No. NOO0l4-97-1-0934

Structural, Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Nanocrystalline Materials: Synthesis, Characterization and Application

This book is a collection of the research articles and review article, published in special issue "Structural, Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Nanocrystalline Materials: Synthesis, Characterization and Application"

Introduction to physical oceanography

"This textbook covers physical-oceanographic processes, theories, data, and measurements, targeted at upper-division undergraduates and graduate students in oceanography, meteorology, and ocean engineering. In addition to the classical topics, the author includes discussions of heat fluxes, the role of the ocean in climate, the deep circulation, equatorial processes including El Nino, databases used by oceanographers, the role of satellites and data from space, ship-based measurements, and the importance of vorticity in understanding oceanic flows. Students should have studied differential equations and introductory college physics, although math is de-emphasized."--Open Textbook Library.A voyage of discovery -- The historical setting -- The physical setting -- Atmospheric influences -- The oceanic heat budget -- Temperature, salinity, and density -- The equations of motion -- Equations of motion with viscosity -- Response of the upper ocean to winds -- Geostrophic currents -- Wind driven ocean circulation -- Vorticity in the ocean -- Deep circulation in the ocean -- Equatorial processes -- Numerical models -- Ocean waves -- Coastal processes and tides

Numerical Simulation

Nowadays mathematical modeling and numerical simulations play an important role in life and natural science. Numerous researchers are working in developing different methods and techniques to help understand the behavior of very complex systems, from the brain activity with real importance in medicine to the turbulent flows with important applications in physics and engineering. This book presents an overview of some models, methods, and numerical computations that are useful for the applied research scientists and mathematicians, fluid tech engineers, and postgraduate students

Second Microgravity Fluid Physics Conference

The conference's purpose was to inform the fluid physics community of research opportunities in reduced-gravity fluid physics, present the status of the existing and planned reduced gravity fluid physics research programs, and inform participants of the upcoming NASA Research Announcement in this area. The plenary sessions provided an overview of the Microgravity Fluid Physics Program information on NASA's ground-based and space-based flight research facilities. An international forum offered participants an opportunity to hear from French, German, and Russian speakers about the microgravity research programs in their respective countries. Two keynote speakers provided broad technical overviews on multiphase flow and complex fluids research. Presenters briefed their peers on the scientific results of their ground-based and flight research. Fifty-eight of the sixty-two technical papers are included here

Thermal Flows

Flows of thermal origin and heat transfer problems are central in a variety of disciplines and industrial applications. The present book entitled Thermal Flows consists of a collection of studies by distinct investigators and research groups dealing with different types of flows relevant to both natural and technological contexts. Both reviews of the state-of-the-art and new theoretical, numerical and experimental investigations are presented, which illustrate the structure of these flows, their stability behavior, and the possible bifurcations to different patterns of symmetry and/or spatiotemporal regimes. Moreover, different categories of fluids are considered (liquid metals, gases, common fluids such as water and silicone oils, organic and inorganic transparent liquids, and nanofluids). This information is presented under the hope that it will serve as a new important resource for physicists, engineers and advanced students interested in the physics of non-isothermal fluid systems; fluid mechanics; environmental phenomena; meteorology; geophysics; and thermal, mechanical and materials engineering