Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
45
2
2018
ANALYSIS OF NON-FOURIER HEAT-CONDUCTION-BASED LATTICE BOLTZMANN MODEL IN TWO-DIMENSIONAL PLATE WITH A HOT SHAFT PASSING THROUGH IT
93-104
Ahmad Reza
Rahmati
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
A.
Gheibi
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
In the present work, two-dimensional (2D) heat wave propagation in a 2D plate with a hot shaft passing through it is analyzed. It is assumed that the shaft is connected to a heat source so that it has constant temperature. Time lag between the imposition of a discrete thermal disturbance on the shaft, the right and north boundaries, and manifestation of its effect is accounted by considering finite propagation speed of the conduction wave. In order to obtain temperature
distribution in the plate, the lattice Boltzmann method (LBM) for the analysis of non-Fourier heat conduction is
employed. The LBM results are validated against those available in the literature and in some comparison studies, a finite difference solution is also obtained. The comparisons of the results show that there is excellent agreement between them.
PRESSURE LOSSES FOR TURBULENT FLOW THROUGH BENDS IN SERIES
105-128
Blake T.
Petersen
Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE,
Minneapolis, Minnesota 55455, USA
John M.
Gorman
Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE,
Minneapolis, Minnesota 55455, USA
Eph M.
Sparrow
Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE,
Minneapolis, Minnesota 55455, USA
The pressure loss caused by a single isolated bend, which receives a fully developed flow and allows the flow to return to a fully developed state in its downstream tangent, is well documented and understood. However, when two or more
bends are separated by a length insufficient to restore fully developed flow, the truncation of the pressure loss occurring downstream of the first bend and the distorted flow received by the second bend prevent the extrapolated use of singlebend data for the two-bend case. Using numerical simulation, a comprehensive investigation of the pressure losses caused by two-bend combinations was performed. Two in-plane bend combinations, having a "U" and "S" shape, and an out-of-plane bend combination were examined. For each bend combination, simulations were performed for many separating lengths ranging from zero to 100 pipe diameters for Reynolds numbers of 2·105, 5·104, and 1·104. For the "U" combination, the two-bend pressure loss decreased monotonically as the separating distance decreased. For the "S" and out-of-plane configurations, the pressure loss was at a minimum when the separating length was between three and five pipe diameters. This is consistent with the existing results from the highest quality experiments on the topic. In addition to results, the present work presents a fundamentals-based comprehensive explanation of the observed pressure loss trends using dimensionless quantities to measure the distortion of the flow at cross sections within the bend combination.
OPTIMUM GEOMETRY FOR NATURAL CONVECTION CHANNEL FLOW WITH INTERNAL HEATED SLATS
129-137
C. Y.
Wang
Department of Mathematics and Mechanical Engineering, Michigan State University, East
Lansing, Michigan 48824, USA
Moving minute amount of fluids is important in microfluidics. The present work is a preliminary study of using
a natural convection pump as a means to do that. The model consists of periodic heated vertical slats enclosed by
constant temperature plates. Assuming a fully developed state, the problem is solved for the net through flow using
eigenfunction expansions and point match. Optimum geometric dimensions for the maximal flow are determined.
ANALYSIS AND INVESTIGATION OF THE ADAPTIVE TECHNIQUE TO SIMULATE THE SYNTHETIC JET SYSTEM
139-152
Khadidja
Boualem
Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf, USTO-MB, BP 1505, El M'naouer, 31000 Oran Algérie
Tayeb
Yahiaoui
Laboratoire d’Aéronautique et Systèmes Propulsive, Université des Sciences et de la
Technologie d’Oran - Mohamed-Boudiaf, Algeria
Abbes
Azzi
Laboratory of Naval Aero-Hydrodynamic, Faculty of Mechanical Engineering, Oran
University of Sciences and Technology, PO Box 1505, El-Mnaouar Oran, Algeria
Synthetic jets are used in several fields because of their simplicity and efficiency, such as active cooling to improve
thermal management and active control of the boundary layer separation in various application practices, in order
to enhance aerodynamic performance. These devices are generated by a piezoelectric diaphragm embedded in a cavity,
through an orifice, in a periodic manner. Also, they have the benefit of being compact with zero net mass flux. To
study the synthetic jets experimentally, many practical devices can be used, such as artificial excitation, micro valves, pneumatic, etc. Analytically, several approaches were previously used, such as the theory of plate deformation, a lumped element model based on electroacoustic theory, periodic inlet velocity profiles, etc. In the present study, a numerical approach based on a moving mesh method is proposed in the modeling field as a new approach. The mesh deformation is an important approach component for solving problems with moving boundaries or deformable bodies. The motion might be imposed or an implicit part of a coupled fluid-structure simulation. The new model was compared to theory of plates deformation approach, which has previously been used, and both are validated by the experimental data (given in a NASA workshop on Synthetic Jets Validation CFDVAL2004) to evaluate the performed one. Results show that the flow behavior is reproduced correctly by the new approach.
ANALYTICAL STUDY OF NONCONTINUUM FLOW IMPINGEMENT ONTO A FLAT PLATE WITH AN ARBITRARY ANGLE
153-162
Khaleel R.
Al Khasawneh
Department of Mechanical Engineering, Jordan University of Science and Technology, Irbid
Duaa
Kharouf
Department of Mechanical Engineering, Jordan University of Science and Technology, Irbid
This work analyzes rarefied plume impingement on a flat plate with an arbitrary angle. For this problem, due to the
rarefication effects we must use nontraditional analysis methods. A rarefied jet gas flows out of a two-dimensional
nozzle and impinging on a flat plate was investigated with a gaskinetic method. With a relation between velocity directions and geometry positions, the corresponding sets of analytical solutions for the density, slip velocity, temperature, pressure, shear stress, and heat flux on locations very close or right on the flat plate were obtained. Numerical simulation results obtained with the direct simulation Monte Carlo method validate these analytical solutions. In general, the comparisons between the complex exact analytical solutions and the numerical results are virtually identical.
STARTING FLOW IN AN ELLIPTIC DUCT
163-170
C. Y.
Wang
Department of Mathematics and Mechanical Engineering, Michigan State University, East
Lansing, Michigan 48824, USA
The starting flow in an elliptic duct is solved by eigenfunction superposition. The symmetric-symmetric eigenfunctions and eigenvalues for the ellipse are found by an efficient Ritz method. Velocity profiles and transient flow rates are determined.
INVESTIGATION ON THE EFFECT OF AXIALLY MOVING CARBON NANOTUBE, NANOFLOW, AND KNUDSEN NUMBER ON THE VIBRATIONAL BEHAVIOR OF THE SYSTEM
171-186
Soheil
Oveissi
Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
Davood Semiromi
Toghraie
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University,
Khomeinishahr, Iran
S. Ali
Eftekhari
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University,
Khomeinishahr, Iran
The equation of motion of the axially moving carbon nanotube conveying fluid is obtained in order to investigate the
effect of the velocity of axially moving CNT and internal flowing fluid on the vibrational behavior of the system. To
this end, the nonlocal continuum theory is used to consider the small-scale effect and the Knudsen number is employed
to create the nanoflow as a fluid passing through the CNT. The equation of motion is obtained by using Hamilton's
principle and the Galerkin method is used to discretize and solve it. The results indicate that the small-scale parameter plays a key role in determining the critical velocity values and the occurring instabilities of the system. It is obvious that for the eigenfunction in the higher modes, the imaginary parts of the eigenvalues reach zero at a lower critical velocity in longitudinal vibration of the axially moving CNT conveying fluid. Moreover, it can be found that the stability of the system decreases when the axially moving CNT conveying fluid is considered with the constant axial movement velocity of the CNT, the constant fluid velocity, and the case in which both velocities are the same, respectively. Also, the existence of the fluid could cause an approximately 0.2% reduction in the magnitude of the system critical velocity, and then the system's stability decreases.