scholarly journals INTAKE: a numerical program to calculate fluid velocity profiles near a rectangular inlet in a stream with cross flow

1973 ◽  
Author(s):  
L. Dresner ◽  
V. R. Cain ◽  
W. Jr. Davis
Keyword(s):  
Fluid Velocity ◽  
Cross Flow ◽  
Velocity Profiles ◽  
Numerical Program

Designing Fluid Velocity Profiles for Optimal Primary Cementing

1996 ◽  
Author(s):  
M.G.P. SILVA ◽  
A.L. Martins ◽  
B.C. BARBOSA ◽  
H. Garcia
Keyword(s):  
Fluid Velocity ◽  
Velocity Profiles ◽  
Primary Cementing

Linear optimal control applied to instabilities in spatially developing boundary layers

2002 ◽  
Vol 470 ◽  
pp. 151-179 ◽  
Author(s):  
MARKUS HÖGBERG ◽  
DAN S. HENNINGSON
Keyword(s):  
Optimal Control ◽  
Cross Flow ◽  
Velocity Profiles ◽  
Base Flow ◽  
Optimal Feedback Control ◽  
Linear Optimal Control ◽  
Convolution Kernels ◽  
Tollmien Schlichting ◽  
Layer Flow ◽  
Parallel Case

The work presented extends previous research on linear controllers in temporal channel flow to spatially evolving boundary layer flow. The flows studied are those on an infinite swept wedge described by the Falkner–Skan–Cooke (FSC) velocity profiles, including the special case of the flow over a flat plate. These velocity profiles are used as the base flow in the Orr–Sommerfeld–Squire equations to compute the optimal feedback control through blowing and suction at the wall utilizing linear optimal control theory. The control is applied to a parallel FSC flow with unstable perturbations. Through an eigenvalue analysis and direct numerical simulations (DNS), it is shown that instabilities are stabilized by the controller in the parallel case. The localization of the convolution kernels for control is also shown for the FSC profiles.Assuming that non-parallel effects are small a technique is developed to apply the same controllers to a DNS of a spatially evolving flow. The performance of these controllers is tested in a Blasius flow with both a Tollmien–Schlichting (TS) wave and an optimal spatial transiently growing perturbation. It is demonstrated that TS waves are stabilized and that transient growth is lowered by the controller. Then the control is also applied to a spatial FSC flow with unstable perturbations leading to saturated cross-flow vortices in the uncontrolled case. It is demonstrated that the linear controller successfully inhibits the growth of the cross-flow vortices to a saturated level and thereby delays the possibility of transition through secondary instabilities. It is also demonstrated that the controller works for relatively high levels of nonlinearity, and for stationary as well as time-varying perturbations.

scholarly journals An electromagnetic arrayed pump to create arbitrary velocity profiles in fluid

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Seyed Peyman Hashemi ◽  
Mohammad Reza Karafi ◽  
Mohammad Hossein Sadeghi ◽  
Vahid Rezaei Esfedan
Keyword(s):  
Magnetic Field ◽  
Fluid Velocity ◽  
Rectangular Channel ◽  
Velocity Profiles ◽  
List Type ◽  
Finite Element Software ◽  
Electromagnetic Pump ◽  
Naoh Solution ◽  
Arbitrary Velocity ◽  
The Magnetic Field

AbstractThe present paper is conducted to develop a new structure of an electromagnetic pump capable of controlling the magnetic field in a rectangular channel. Common electromagnetic pumps do not create uniform velocity profiles in the cross-section of the channel. In these pumps, an M-shape profile is created since the fluid velocity in the vicinity of the walls is higher than that in its center. Herein, the arbitrary velocity profiles in the electromagnetic pump are generated by introducing an arrayed structure of the coils in the electromagnetic pump and implementing 3D numerical simulation in the finite element software COMSOL. The dimensions of the rectangular channel are 5.5 × 150 mm2. Moreover, the magnetic field is provided using a core with an arrayed structure made of low-carbon iron, as well as five couples of coils. 20% NaoH solution is utilized as the fluid (conductivity: 40 S/m). The arrayed pump is fabricated and experimentally created an arbitrary velocity profile. The pressure of the pump in every single array is 12 Pa and the flow rate is equal to 3375 mm3/s. According to the results, there is a good agreement between the experimental test carried out herein and the simulated models.Article highlights This is the first time that the idea of arrayed electromagnetic pump is presented. This pump uses a special arrayed core with coils; by controlling the current of each coil and the direction of the currents, the magnetic field under the core could be adjusted. By changing the magnetic field at any position in the width of the channel, the Lorentz force alters, which leads to different velocity and pressure profiles. Using COMSOL multiphysics software, the electromagnetic pump was simulated in real size compared to the experimental model. Subsequently, the simulation model was verified and different velocity profiles were generated by activation and deactivation of different coils. The pressure and velocity curves and contours were extracted. The experimental setup was manufactured and assembled. NaOH solution was utilized as the fluid. Afterwards, different modes of coil activations were investigated and the pressure and velocity profiles of the pump were calculated.

Phase Lag Model for Fluidelastic Instability in Square Cylinder Arrangement

2015 ◽  
Author(s):  
Mustapha Benaouicha ◽  
Elisabeth Longatte ◽  
Franck Baj
Keyword(s):  
Dynamic Instability ◽  
Fluid Velocity ◽  
Cross Flow ◽  
Theoretical Models ◽  
Phase Lag ◽  
Structure Parameters ◽  
Square Cylinder ◽  
Theoretical Formulation ◽  
Lag Model ◽  
Pitch Ratio

In this paper, a phase lag model is proposed in order to predict the fluid velocity threshold for fluidelastic dynamic instability of a square cylinder arrangement under cross flow. A theoretical formulation of a total damping, including the added damping in still fluid, the damping due to fluid flow and the damping derived from the phase shift between the fluid force and tube displacement, is given. A function of fluid and structure parameters, such as reduced velocity, pitch ratio and Scruton number, is thus obtained. It is shown that this function, taken as function of the reduced velocity variable, vanishes at the critical reduced velocity from which the fluidelastic dynamic instability of the tube occurs. Obviously, the value of the critical velocity is depending on other fluid-structure parameters. The obtained results are compared to experimental ones and those obtained from other theoretical models.

Non-Newtonian Fluid Velocity Profiles Determined with Simple Magnetic Resonance Spin Echoes

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Jiangfeng Guo ◽  
Michael M. B. Ross ◽  
Benedict Newling ◽  
Bruce J. Balcom
Keyword(s):  
Magnetic Resonance ◽  
Newtonian Fluid ◽  
Fluid Velocity ◽  
Velocity Profiles ◽  
Resonance Spin ◽  
Spin Echoes

The Second Law Analysis of Thermodynamics for the Plate–Fin Surface Performance in a Cross Flow Heat Exchanger

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mansour Nasiri Khalaji ◽  
Isak Kotcioglu ◽  
Sinan Caliskan ◽  
Ahmet Cansiz
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Entropy Generation ◽  
Fluid Velocity ◽  
Cross Flow ◽  
Design Parameters ◽  
Second Law ◽  
Transfer Unit ◽  
Pin Fins

In this paper, a particular heat exchanger is designed and analyzed by using second law of thermodynamics. The heat exchanger operates with the cross flow forced convection having cylindrical, square, and hexagonal pin fins (tubular router) placed in the rectangular duct. The pin fins are installed periodically at the top and bottom plates of the duct perpendicular to the flow direction, structured in-line, and staggered sheet layouts. The entropy generation in the flow domain of the channels is calculated to demonstrate the rate of irreversibilities. To obtain the efficiencies, irreversibility, thermal performance factor, and entropy generation number (EGN), the heat exchanger is operated at different temperatures and flow rates by using hot and cold fluids. Optimization of the design parameters and winglet geometry associated with the performance are determined by entropy generation minimization. The variation of the EGN with Reynolds number for various tubular routers is presented. The Reynolds number is determined according to the experimental plan and the performance is analyzed with the method of effectiveness—number of transfer unit (NTU). Based on particular designs, it was determined that the increment in fluid velocity enhances the heat transfer rate, which in turn decreases the heat transfer irreversibility.

scholarly journals Numerical Analysis of Unsaturated Soil Slopes under Rainfall Infiltration Based on the Modified Glasgow Coupled Model

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Guoqing Cai ◽  
Mengzi Li ◽  
Bowen Han ◽  
Kenan Di ◽  
Qianqian Liu ◽  
...  
Keyword(s):  
Unsaturated Soil ◽  
Fluid Velocity ◽  
Coupled Model ◽  
Rainfall Infiltration ◽  
Secondary Development ◽  
Infiltration Process ◽  
Integration Algorithm ◽  
Soil Slopes ◽  
Implicit Integration Algorithm ◽  
Numerical Program

An ABAQUS UMAT subroutine was used for the secondary development of the established coupled hydromechanical constitutive model of unsaturated soil considering the effect of the microscopic pore structure. Combined with Euler’s backward implicit integration algorithm, a numerical program was established for simulating the proposed model. The developed numerical program was used to simulate the rainfall infiltration process of an actual slope engineering example, and the effects of rainfall intensity and rainfall duration on the pore pressure, fluid velocity, and displacement of the unsaturated soil slope were analyzed. The results show that the developed numerical program can reasonably analyze the changes in the seepage field and displacement field of unsaturated soil slopes under rainfall infiltration.

Vortex-Induced Vibration and Coincident Current Velocity Profiles for a Deepwater Drilling Riser

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
T. Srivilairit ◽  
L. Manuel
Keyword(s):  
Current Velocity ◽  
Field Data ◽  
Numerical Technique ◽  
Spatial Coherence ◽  
Cross Flow ◽  
Velocity Profiles ◽  
Vortex Induced Vibration ◽  
Deepwater Drilling ◽  
Acceleration Data ◽  
Lock In

The objective of this study is to use full-scale field data on current velocities and riser motions to better understand the behavior of deepwater drilling risers. The data are comprised of riser accelerations and coincident current velocity profiles from the monitoring of vortex-induced vibration (VIV) of a drilling riser located at a 1000 m water depth site. Proper orthogonal decomposition (POD), an efficient numerical technique for characterizing the spatial coherence in a random field, is employed here to identify energetic current profiles. The accuracy resulting from the use of only a limited number of the most important POD modes is studied by comparing measured current velocity profiles with those reconstructed based on a reduced-order truncation. In addition to studying current velocity profiles, riser acceleration data from this deepwater drilling riser are also analyzed. In order to analyze the VIV response of this riser, in-line and cross-flow motions in different data segments are studied. Again, empirical POD procedures are employed—this time to derive energetic spatial vibration modes defining the riser motion. Importantly, these modes are identified without the need for either an analytical/computational model of the riser or any physical dimensions and material properties; instead, they are derived exclusively using the field data. Relationships between riser response and coincident current velocity profiles are investigated, especially for those data segments associated with observed lock-in response.

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