Sur le granite orbiculaire de Tisselliline (Hoggar, Sahara central)

1961 ◽  
Vol S7-III (2) ◽  
pp. 174-181
Author(s):  
Jacques Grolier
Keyword(s):  
Small Area ◽  
Diffusion Theory ◽  
Double Diffusion ◽  
Chemical Study ◽  
Granite Outcrops ◽  
Central Sahara ◽  
Northern Edge

Abstract Orbicular granite outcrops in a small area near the northern edge of the Tisselliline granitic massif in the Ahaggar mountains (Algeria) in the central Sahara. Petrographic and chemical study leads to a double diffusion theory of its origin. Whereas orbicular rocks are generally found near a migmatite front, this particular example indicates that an orbicular facies can also be associated with small granite massifs, thus suggesting the possibility that a phase analogous to migmitization may be involved in the genesis of certain intrusive massifs of this type.

Entropy generation analysis on unsteady flow of Maxwell nanofluid over the stretched wedge with Cattaneo-Christov double diffusion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yu Bai ◽  
Huiling Fang ◽  
Yan Zhang
Keyword(s):  
Mass Transfer ◽  
Unsteady Flow ◽  
Heat And Mass Transfer ◽  
Entropy Generation ◽  
Diffusion Theory ◽  
Double Diffusion ◽  
Convective Boundary ◽  
Concentration Difference ◽  
Content Type ◽  
Maxwell Nanofluid

Purpose This paper aims to present the effect of entropy generation on the unsteady flow of upper-convected Maxwell nanofluid past a wedge embedded in a porous medium in view of buoyancy force. Cattaneo-Christov double diffusion theory simulates the processes of energy phenomenon and mass transfer. Meanwhile, Brownian motion, thermophoresis and convective boundary conditions are discussed to further visualize the heat and mass transfer properties. Design/methodology/approach Coupled ordinary differential equations are gained by appropriate similar transformations and these equations are manipulated by the Homotopy analysis method. Findings The result is viewed that velocity distribution is a diminishing function with boosting the value of unsteadiness parameter. Moreover, fluid friction irreversibility is dominant as the enlargement in Brinkman number. Then controlling the temperature and concentration difference parameters can effectively regulate entropy generation. Originality/value This paper aims to address the effect of entropy generation on unsteady flow, heat and mass transfer of upper-convected Maxwell nanofluid over a stretched wedge with Cattaneo-Christov double diffusion, which provides a theoretical basis for manufacturing production.

Thermal energy transport in Burgers nanofluid flow featuring the Cattaneo–Christov double diffusion theory

2020 ◽  
Vol 10 (12) ◽  
pp. 5331-5342 ◽  
Author(s):  
Zahoor Iqbal ◽  
Masood Khan ◽  
Awais Ahmed ◽  
Jawad Ahmed ◽  
Abdul Hafeez
Keyword(s):  
Thermal Energy ◽  
Energy Transport ◽  
Diffusion Theory ◽  
Double Diffusion ◽  
Nanofluid Flow ◽  
Thermal Energy Transport

Rotational flow of Oldroyd-B nanofluid subject to Cattaneo-Christov double diffusion theory

2020 ◽  
Vol 41 (7) ◽  
pp. 1083-1094 ◽  
Author(s):  
A. Hafeez ◽  
M. Khan ◽  
A. Ahmed ◽  
J. Ahmed
Keyword(s):  
Diffusion Theory ◽  
Double Diffusion ◽  
Rotational Flow

DMP XIV: Prehistoric sites in the Wadi Barjuj, Fazzan, Libyan Sahara

2011 ◽  
Vol 42 ◽  
pp. 117-138 ◽  
Author(s):  
Marta Mirazón Lahr ◽  
Robert Foley ◽  
Federica Crivellaro ◽  
José Maillo Fernandez ◽  
Alex Wilshaw ◽  
...  
Keyword(s):  
Small Area ◽  
Low Frequency ◽  
Resource Base ◽  
Hunter Gatherers ◽  
Late Stone Age ◽  
Northern Edge ◽  
Grinding Stones ◽  
The Rich ◽  
Mode 3 ◽  
Cut And Fill

AbstractThis paper reports on the fifth season of fieldwork for the Palaeoanthropology part of the Desert Migrations Project. Previous seasons established an extensive archaeological map based on a wide survey of the rich record along the edges of the Ubari Sand Sea, a small area of the Messak Settafet, the Wadi al-Ajal, the Wadi ash-Shati and the Wadi Barjuj. These surveys, complemented with small excavations, demonstrated a deep prehistory to the Fazzan, with Mode 1 technologies, Acheulean, Mode 3 (classic Levallois, large blade technologies, and Aterian), and Late Stone Age and Neolithic assemblages, some with pottery and grinding stones. The focus of the 2011 season was the Wadi Barjuj. This is an extensive wadi system to the South of the Messak, running along the northern edge of the Murzuq Sand Sea, and draining towards the east. Geomorphologically, it comprises old channel cut and fill gravels, usually finely graded, with areas of ancient lacustrine duricrusts, some of which are elevated significantly above the landscape. Surveys, complementing those of 2008, revealed a particularly rich and extensive Holocene series of sites, with microliths, pottery and grinding stones. These sites indicate a dense early Holocene occupation which seems associated with both hunter-gatherers and pastoralists. In addition, there was a low frequency of MSA lithics (compared to other survey areas), although one extremely rich site (BJJ4) had a very large number of water-worn, highly diagnostic small bifaces, characteristics of some Africa MSA traditions. Acheulean was relatively rare. One restricted locality (BJJ6) provided further evidence for a Mode 1 presence in the region, similar to that reported earlier from the Messak and Wadi ash-Shati (Mirazón Lahr et al. 2009, 2010). The context for the finds suggests that at various points during the Pleistocene the Wadi Barjuj was a low lying, swampy and/or lacustrine region, possibly riverine at times, and attractive to hominin populations because of its relatively rich resource base. This paper describes the localities and finds underpinning these conclusions.

Consequences of Fourier’s and Fick’s laws in bioconvective couple stress nanofluid flow configured by an inclined stretchable cylinder

2021 ◽  
Vol 35 (17) ◽  
pp. 2150176
Author(s):  
Hassan Waqas ◽  
Taseer Muhammad ◽  
Sajjad Hussain ◽  
Sumeira Yasmin ◽  
Ghulam Rasool
Keyword(s):  
Couple Stress ◽  
Diffusion Theory ◽  
Variable Temperature ◽  
Thermal Relaxation ◽  
Coupled System ◽  
Double Diffusion ◽  
Solid Particles ◽  
Nonlinear Thermal Radiation ◽  
Temperature Conductivity ◽  
Fluid Parameters

The main benefits of submerging tiny-solid particles with the host fluid are to enhance the capability of storing heat, heat exchanger and interaction between the nanomaterials. The objective of this paper is to investigate the steady flow of bio-convective couple stress nanofluid across an inclined stretching cylinder with activation energy, motile microorganisms and nonlinear thermal radiation. The variable temperature conductivity and diffusivity impacts are considered. The Cattaneo–Christov double diffusion theory is also accounted in this model. The governing primary equations are reduced into a coupled system of ODEs by adopting appropriate similarity transformation. The resulting system is integrated numerically utilizing bvp4c tool via MATLAB software. The physical properties of concerned parameters against subjective profiles are examined through tabular and pictorial outline and then discussed in bit detail. It is shown that the velocity field reduces with growing estimations of Reynolds number and buoyancy ratio parameter. It is analyzed that thermal distribution decreases with improving amount of thermal relaxation parameter. Furthermore, concentration of nanoparticles is enhanced for larger amount of thermophoresis parameter. The microorganism field is up surged with enlarging amount of curvature and couple stress fluid parameters.

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