scholarly journals Suction Injection Induced MHD Flow through Vertical Narrow Porous Channel with Permeable Properties

2019 ◽  
Vol 8 (4) ◽  
pp. 121-126
Keyword(s):  
Transverse Velocity ◽  
Rectangular Channel ◽  
Fluid Flows ◽  
Mhd Flow ◽  
Research Problem ◽  
Velocity Profiles ◽  
Current Research Problem ◽  
Flow Equations ◽  
Electrically Conducting ◽  
Permeability Parameter

The current research problem deals with fluid flows that are electrically conducting known as Magnetohydrodynamic(MHD) flow, viscous oscillatory and stratified fluid in a vertical long small geometry rectangular channel that has permeable property with one side being porous and the other side being nonporous. Corresponding fluid flow equations are simplified and hence solved by applying Lubrication approximation by using similarity transformation. The interpretations of the influences of various quantities that are involved to the problem on velocity profiles, pressure and density distributions are explained in detail. The results of the research problem shows that the Magnetohydrodynamic parameter encourages backflow nearer to the boundaries of the channel while permeability parameter influences the flow differently for axial and transverse velocity profiles. The results for =0 reduces to the results that are already available in the literature.The current research problem deals with fluid flows that are electrically conducting known as Magnetohydrodynamic(MHD) flow, viscous oscillatory and stratified fluid in a vertical long small geometry rectangular channel that has permeable property with one side being porous and the other side being nonporous. Corresponding fluid flow equations are simplified and hence solved by applying Lubrication approximation by using similarity transformation. The interpretations of the influences of various quantities that are involved to the problem on velocity profiles, pressure and density distributions are explained in detail. The results of the research problem shows that the Magnetohydrodynamic parameter encourages backflow nearer to the boundaries of the channel while permeability parameter influences the flow differently for axial and transverse velocity profiles. The results for =0 reduces to the results that are already available in the literature.

LES AND "IN VITRO" EXPERIMENTAL VALIDATION OF FLOW AROUND A TEETH-SHAPED OBSTACLE

2010 ◽  
Vol 02 (02) ◽  
pp. 265-279 ◽  
Author(s):  
ANNEMIE VAN HIRTUM ◽  
XAVIER GRANDCHAMP ◽  
XAVIER PELORSON ◽  
KAZUNORI NOZAKI ◽  
SHINJI SHIMOJO
Keyword(s):  
Sound Production ◽  
Transverse Velocity ◽  
Rectangular Channel ◽  
Physical Modelling ◽  
Velocity Profiles ◽  
Measured Data ◽  
Flow Data ◽  
Mean Velocity ◽  
Single Sensor

The current paper aims to provide numerical and experimental flow data relevant for physical modelling of human fricative sound production due to the interaction of airflow with the teeth. A simplified upper incisor-palate geometry is derived from typical morphological features. The geometry is inserted in a rectangular channel for which the width-to-height ratio yields 4. The obstruction degree due to the presence of the simplified upper incisor yields 70%. Numerical flow data are obtained from large eddy simulations. Experimental flow data are gathered from single-sensor anemometry on a rigid plaster print of the computational grid. Transverse velocity profiles are obtained downstream in the constricted area, i.e., from x = 0 up to x/h = 1.5 with h denoting the aperture height. The Reynolds number is set to 4000. The mean velocity profiles derived on simulated and measured data exhibit a strong asymmetry due to the presence of the obstruction. Nevertheless, significant differences appear with respect to the jet development, as e.g., quantified by the downstream evolution of the jet width or the appearance of significant turbulence intensities (>10%) at the teeth edge in the measured data whereas the simulated flow remains laminar.

Toward full simulations for a liquid metal blanket. Part 2: Computations of MHD flows with volumetric heating for a PbLi blanket prototype at Ha~104 and Gr~1012

2021 ◽  
Author(s):  
Long Chen ◽  
Sergey Smolentsev ◽  
Ming-Jiu Ni
Keyword(s):  
Pressure Drop ◽  
Liquid Metal ◽  
Mhd Flow ◽  
Mhd Flows ◽  
Volumetric Heating ◽  
Flow Equations ◽  
Electrically Conducting ◽  
Fine Mesh ◽  
Fusion Neutrons ◽  
Flow Effects

Abstract On the pathway toward full simulations for a liquid metal blanket, this Part 2 extends a previous study of purely MHD flows in a DCLL blanket in Ref. 1 [Chen, L., Smolentsev, S., and Ni, M. J. (2020)] to more general conditions when the MHD flow is coupled with heat transfer. The simulated prototypic blanket module includes all components of a real liquid metal blanket system, such as supply ducts, inlet and outlet manifolds, multiple poloidal ducts and a U-turn zone. Volumetric heating generated by fusion neutrons is added to simulate thermal effects in the flowing PbLi breeder. The MHD flow equations and the energy equation are solved with a DNS-type finite-volume code “MHD-UCAS” on a very fine mesh of 470×10^6 cells. The applied magnetic field is 5 T (Hartmann number Ha~10^4), the PbLi velocity in the poloidal ducts is 10 cm/s (Reynolds number Re~10^5), whereas the maximum volumetric heating is 30 MW/m^3 (Grashof number Gr~10^12). Four cases have been simulated, including forced- and mixed-convection flows, and either an electrically conducting or insulating blanket structure. Various comparisons are made between the four computed cases and also against the purely MHD flows computed earlier in Ref. \cite{1} with regards to the (1) MHD pressure drop, (2) flow balancing, (3) temperature field, (4) flows in particular blanket components, and (5) 3D and turbulent flow effects. The strongest buoyancy effects were found in the poloidal ducts. In the electrically non- conducting blanket, the buoyancy forces lead to significant modifications of the flow structure, such as formation of reverse flows, whereas their effect on the MHD pressure drop is relatively small. In the electrically conducting blanket case, the buoyancy effects on the flow and MHD pressure drop are almost negligible.

Hall effects on MHD flow past an accelerated plate

1980 ◽  
Vol 23 (3) ◽  
pp. 495-500
Author(s):  
V. M. Soundalgekar ◽  
S. Ravi ◽  
S. B. Hiremath
Keyword(s):  
Exact Solution ◽  
Viscous Fluid ◽  
Skin Friction ◽  
Infinite Plate ◽  
Mhd Flow ◽  
Velocity Profiles ◽  
Electrically Conducting ◽  
Flow Past ◽  
Hall Effects ◽  
Hall Parameter

An exact solution of the MHD flow of an incompressible, electrically conducting, viscous fluid past a uniformly accelerated infinite plate has been presented. The velocity profiles are shown graphically and the numerical values of axial and transverse components of skin friction are tabulated. At high values of the Hall parameter, wt, the velocity is found to be oscillatory near the plate.

scholarly journals Resource Controllability of Business Processes Under Conditional Uncertainty

2021 ◽  
Author(s):  
Matteo Zavatteri ◽  
Carlo Combi ◽  
Luca Viganò
Keyword(s):  
Access Control ◽  
Business Process ◽  
Process Management ◽  
Business Processes ◽  
Autonomous Systems ◽  
Research Problem ◽  
Current Research Problem ◽  
Constraint Networks ◽  
Process Engine ◽  
A Current

AbstractA current research problem in the area of business process management deals with the specification and checking of constraints on resources (e.g., users, agents, autonomous systems, etc.) allowed to be committed for the execution of specific tasks. Indeed, in many real-world situations, role assignments are not enough to assign tasks to the suitable resources. It could be the case that further requirements need to be specified and satisfied. As an example, one would like to avoid that employees that are relatives are assigned to a set of critical tasks in the same process in order to prevent fraud. The formal specification of a business process and its related access control constraints is obtained through a decoration of a classic business process with roles, users, and constraints on their commitment. As a result, such a process specifies a set of tasks that need to be executed by authorized users with respect to some partial order in a way that all authorization constraints are satisfied. Controllability refers in this case to the capability of executing the process satisfying all these constraints, even when some process components, e.g., gateway conditions, can only be observed, but not decided, by the process engine responsible of the execution. In this paper, we propose conditional constraint networks with decisions (CCNDs) as a model to encode business processes that involve access control and conditional branches that may be both controllable and uncontrollable. We define weak, strong, and dynamic controllability of CCNDs as two-player games, classify their computational complexity, and discuss strategy synthesis algorithms. We provide an encoding from the business processes we consider here into CCNDs to exploit off-the-shelf their strategy synthesis algorithms. We introduce $$\textsc {Zeta}$$ Z E T A , a tool for checking controllability of CCNDs, synthesizing execution strategies, and executing controllable CCNDs, by also supporting user interactivity. We use $$\textsc {Zeta}$$ Z E T A to compare with the previous research, provide a new experimental evaluation for CCNDs, and discuss limitations.

scholarly journals Combined effect of free and forced convection on MHD flow in a rotating porous channel

1982 ◽  
Vol 5 (1) ◽  
pp. 165-182 ◽  
Author(s):  
D. R. V. Prasada Rao ◽  
D. V. Krishna ◽  
Lokenath Debnath
Keyword(s):  
Magnetic Field ◽  
Forced Convection ◽  
Fluid Flows ◽  
Mhd Flow ◽  
Combined Effect ◽  
Porous Channel ◽  
Shear Stresses ◽  
Mass Rate ◽  
Flow Parameters ◽  
Free And Forced Convection

This paper gives a steady linear theory of the combined effect of the free and forced convection in rotating hydromagnetic viscous fluid flows in a porous channel under the action of a uniform magnetic field. The flow is governed by the Grashof numberG, the Hartmann numberH, the Ekman numberE, and the suction Reynolds numberS. The solutions for the velocity field, temperature distribution, magnetic field, mass rate of flow and the shear stresses on the channel boundaries are obtained using a perturbation method with the small parameterS. The nature of the associated boundary layers is investigated for various values of the governing flow parameters. The velocity, the temperature, and the shear stresses are discussed numerically by drawing profiles with reference to the variations in the flow parameters.

scholarly journals Effects of ohmic heating and viscous dissipation on steady MHD flow near a stagnation point on an isothermal stretching sheet

2009 ◽  
Vol 13 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Pushkar Sharma ◽  
Gurminder Singh
Keyword(s):  
Stagnation Point ◽  
Viscous Dissipation ◽  
Ohmic Heating ◽  
Mhd Flow ◽  
Transverse Magnetic ◽  
Skin Friction Coefficient ◽  
Physical Parameters ◽  
Governing Equations ◽  
Shooting Technique ◽  
Electrically Conducting

Aim of the paper is to investigate effects of ohmic heating and viscous dissipation on steady flow of a viscous incompressible electrically conducting fluid in the presence of uniform transverse magnetic field and variable free stream near a stagnation point on a stretching non-conducting isothermal sheet. The governing equations of continuity, momentum, and energy are transformed into ordinary differential equations and solved numerically using Runge-Kutta fourth order with shooting technique. The velocity and temperature distributions are discussed numerically and presented through graphs. Skin-friction coefficient and the Nusselt number at the sheet are derived, discussed numerically, and their numerical values for various values of physical parameters are compared with earlier results and presented through tables.

scholarly journals Effects of Viscous and Joules Dissipation on MHD Flow, Heat and Mass Transfer past a Stretching Porous Surface Embedded in a Porous Medium

2009 ◽  
Vol 14 (3) ◽  
pp. 303-314 ◽  
Author(s):  
S. P. Anjali Devi ◽  
B. Ganga
Keyword(s):  
Porous Medium ◽  
Magnetic Parameter ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Mhd Flow ◽  
Analytic Solutions ◽  
Skin Friction Coefficient ◽  
Porous Surface ◽  
Suction Parameter ◽  
Confluent Hypergeometric Functions

This paper investigates the influence of both viscous and joules dissipation on the problem of magnetohydrodynamic flow past a stretching porous surface embedded in a porous medium. Analytic solutions of the resulting nonlinear non-homogeneous boundary value problem in the case when the plate stretches with a velocity varying linearly with distance, expressed in terms of confluent hypergeometric functions, are presented for the case of prescribed surface temperature. Numerical calculations have been carried out for various values of suction parameter, magnetic field, Prandtl number, Eckert number and Schmidt number. The results show that increases in magnetic parameter decrease both the dimensionless transverse velocity, longitudinal velocity and also the skin friction coefficient. Also, formation of thin boundary layer is observed for higher value of magnetic parameter.

scholarly journals Numerical Study of MHD Flow and Heat Transfer Through Porous Medium Between Two Parallel Plates With Hall and Ion Slip Effects

2020 ◽  
Vol 7 ◽  
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Numerical Study ◽  
Mhd Flow ◽  
Parallel Plates ◽  
Electrically Conducting ◽  
Flow And Heat Transfer ◽  
Slip Effects ◽  
Ion Slip ◽  
Temperature And Pressure

This paper studies the effects of Hall and ion slip on two dimensional incompressible flow and heat transfer of an electrically conducting viscous fluid in a porous medium between two parallel plates, generated due to periodic suction and injection at the plates. The flow field, temperature and pressure are assumed to be periodic functions in ti e ω and the plates are kept at different but constant temperatures. A numerical solution for the governing nonlinear ordinary differential equations is obtained using quasilinearization method. The graphs for velocity, temperature distribution and skin friction are presented for different values of the fluid and geometric parameters.

Similarity Solutions of the MHD Stagnation-Point Flow over a Power-Law Stretching Sheet

2011 ◽  
Vol 52-54 ◽  
pp. 1895-1900
Author(s):  
Jing Zhu ◽  
Lian Cun Zheng ◽  
Xue Hui Chen
Keyword(s):  
Stagnation Point ◽  
Power Law ◽  
Stretching Sheet ◽  
Velocity Ratio ◽  
Similarity Solutions ◽  
Stagnation Point Flow ◽  
Electrically Conducting ◽  
Power Law Exponent ◽  
Permeability Parameter ◽  
Scaling Group Of Transformations

A similarity analysis is performed for a steady laminar boundary layer stagnation-point flow of an electrically conducting fluid in a porous medium subject to a transverse non-uniform magnetic field past a non-linear stretching sheet. A scaling group of transformations is applied to get the invariants. Using the invariants, a third order ordinary differential equation corresponding to the momentum is obtained. We show the existence and uniqueness of convex and concave solutions for the power law exponent, according to the values of magnetic parameter, permeability parameter and velocity ratio parameter.

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