scholarly journals NUMERICAL AND EXPERIMENTAL ANALYSIS OF THE FLOW OVER A COMMERCIAL VEHICLE - PICKUP

2018 ◽  
Vol 17 (2) ◽  
pp. 92
Author(s):  
W. J. G. S. Pinto ◽  
O. Almeida
Keyword(s):  
Wind Tunnel ◽  
Flow Pattern ◽  
Reverse Flow ◽  
Flow Direction ◽  
Original Data ◽  
Cfd Simulations ◽  
Flat Surfaces ◽  
Sharp Edges ◽  
Recirculation Zones ◽  
Low Speed Wind Tunnel

This work presents an ongoing numerical and experimental study of the flow around a pickup vehicle by means of CFD simulations and wind tunnel experiments. The model was based on the light-pickup market in Brazil and it was designed with flat surfaces and sharp edges. One of the objectives of this research was the understanding about the flow pattern around the vehicle, especially in the region behind the cabin and the wake. Another goal was to obtain original data from experimental measurements which could be used on further computational investigations. The experiments were carried out in a low-speed wind tunnel at Reynolds number of 5 x 105. Hot-wire anemometry was used to obtain the velocity profiles. Wall tufts were applied to describe the flow direction and regions of attached/detached and recirculation zones. Acceleration due to the underbody and the shear layer formed on the cabin were well defined, also indicating a region of reverse flow behind the tailgate. The flow visualization allowed the identification of recirculation regions inside the trunk and regions of detached flow. These flow patterns were also reproduced in the CFD simulations resulting satisfactory information to describe the main flow pattern over the pickup vehicle.

CFD Simulations and PIV Measurements for Optimization of Flow Pattern in a Sieve Plate Extraction Column

2011 ◽  
Vol 391-392 ◽  
pp. 1464-1468
Author(s):  
Chang Chun Duan ◽  
Chun Jiang Liu ◽  
Xi Gang Yuan
Keyword(s):  
Flow Pattern ◽  
Reverse Flow ◽  
Continuous Phase ◽  
Extraction Column ◽  
Sieve Plate ◽  
Cfd Simulations ◽  
Flow Area ◽  
Piv Measurements ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd

Present work deals with the optimization for flow pattern of continuous phase in a sieve plate extraction column using both computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) measurements. Firstly single-phase simulation was conducted for the traditional column and it was found that there was a very large reverse flow area between every two plates. Then step by step, by changing the downcomer structure, consisting of inclining downcomers, adding baffles, slotting downcomers and baffles and adjusting the number and size of slots, the reverse flow area was decreased and thereby the flow pattern of continuous phase was optimized. Finally, an optimal flow pattern was obtained with reverse flow area greatly reduced. In order to prove the validity of the simulation results, PIV experiments of two columns were carried out and it was found that the results of simulations and experiments are in good agreement.

scholarly journals Wind tunnel studies of Martian aeolian processes

1974 ◽  
Vol 341 (1626) ◽  
pp. 331-360 ◽  
Keyword(s):  
Surface Roughness ◽  
Wind Tunnel ◽  
Reverse Flow ◽  
Flow Direction ◽  
High Surface ◽  
Geostrophic Wind ◽  
Horseshoe Vortex ◽  
Distinct Pattern ◽  
Dust Storms ◽  
Aeolian Processes

In order to determine the nature of Martian aeolian processes, an investigation is in progress which involves wind tunnel simulations, geologic field studies, theoretical model studies, and analyses of Mariner 9 imagery; this report presents the preliminary results. Threshold speed experiments were conducted for particles ranging in relative density from 1.3 to 11.35 and diameter from 10.2 to 1290 μ m to verify and better define Bagnold’s (1941) expression for grain movement, particularly for low particle Reynolds numbers and to study the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some Martian craters and which indicates that some dark zones around Martian craters are erosional and some light zones are depositional. Analyses of the erosional and depositional zones associated with a 6 m raised rim crater on an open field and a 1.2 km natural impact crater tentatively confirm the wind tunnel results. Application of the wind tunnel results to Mars indicates that for flat surfaces, free stream winds in excess of 400 km/h are required for grain movement. However, lower velocities would be required in regions of high surface roughness, e. g. cratered terrain, and it is proposed that such regions could be zones of origin for some Martian dust storms. Analysis of the Coriolis effect on surface stress shows that surface streaks would be deflected about 15° from the geostrophic wind direction at mid-latitudes.

CFD Simulations of Flows in Step-up Street Canyons

2020 ◽  
Author(s):  
Soo-Jin Park ◽  
Jae-Jin Kim ◽  
Eric Pardyjak ◽  
Ji-Yoon Hong
Keyword(s):  
Wind Tunnel ◽  
Flow Characteristics ◽  
Width Ratio ◽  
Cfd Model ◽  
Wind Tunnel Experiments ◽  
Cfd Simulations ◽  
Street Canyons ◽  
Recirculation Zones ◽  
Computational Fluid Dynamics Cfd ◽  
Two Stages

<p>We analyzed the flow characteristics in strep-up street canyons using a computational fluid dynamics (CFD) model. Simulated results are validated against experimental wind-tunnel results, with the CFD simulations conducted under the same building configurations (H<sub>u</sub>/H<sub>d</sub> = 0.33, 0.6 and L/S = 1, 2, 3, and 4; H<sub>u</sub>, H<sub>d</sub>, L, and S respectively indicate the upwind, downwind building heights, the building length and street-canyon width) as those in the wind-tunnel experiments. The CFD model reproduced the in-canyon vortex, recirculation zones above the downwind buildings, and stagnation point position reasonably well. Furthermore, we analyze the flow characteristics in the step-up street canyons based on the numerical results. The in-canyon flows simulated in the shallow (H<sub>u</sub>/H<sub>d</sub> = 0.33) and deep (H<sub>u</sub>/H<sub>d</sub> = 0.6) street canyons underwent two stages (development and mature stages) as the building-length ratio increased. In the development stages, one clockwise-rotating vortex was formed in the step-up street canyons and its center was slightly tilted toward the wall of the upwind building. However, in the mature stages, two clockwise-rotating vortices were formed in the upper and lower layers. A clockwise vortex and a counterclockwise vortex were stabilized as the building width ratio increased.</p>

An Unsteady Flow Wind Tunnel

1974 ◽  
Vol 25 (2) ◽  
pp. 81-90 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Wind Tunnel ◽  
Unsteady Flow ◽  
Free Stream ◽  
Flow Direction ◽  
Axial Flow ◽  
Mean Velocity ◽  
Low Speed ◽  
The Mean ◽  
Low Speed Wind Tunnel

SummaryA novel low-speed wind tunnel which produces unsteady “gust” flows is described. The walls are sinusoidal in shape and are moved in the flow direction with a velocity Wwless than the mean velocity Wmof the free stream. The tunnel is useful for testing isolated aerofoils and aerofoils in cascade in non-convective gusts (Ww< Wm) so that comparisons with predictions by thin aerofoil theory may be made. However, it does not simulate precisely the unsteady flow that occurs in axial flow turbomachines.

Design Analysis of an Electroless Plating Bath Using CFD Technique

1999 ◽  
Author(s):  
Tien-Yu Tom Lee ◽  
Jong-Kai Lin
Keyword(s):  
Flow Pattern ◽  
Electroless Plating ◽  
Reverse Flow ◽  
Flow Direction ◽  
Low Velocity ◽  
Plating Bath ◽  
Fluid Field ◽  
Plate Design ◽  
Velocity Flow ◽  
Design Options

Abstract The fluid field of the electroless plating bath was analyzed using a Computational Fluid Dynamics Tool. By solving continuity and momentum equations, the pressure and velocity distributions in the plating bath were predicted. The analysis was performed under various design options: flow direction, flowrate, diffuser plate design, and wafer cassette design. It was found that with the reverse flow option; it seems to deliver uniform flow as compared to the forward flow option. Flow pattern was similar among different flowrates and diffuser designs. Low velocity flow always existed at the top portion of the wafer and near the last row of the wafer cassette. With the hypothesis that slower flowrate results in higher plating rate; a qualitative agreement has been observed between the predicted flow pattern and the plated nickel height uniformity.

Design and Construction of a Low Speed Wind Tunnel

2016 ◽  
Author(s):  
Odenir de Almeida ◽  
FREDERICO CARNEVALLI DE MIRANDA ◽  
Olivio Neto ◽  
Fernanda Guimarães Saad
Keyword(s):  
Wind Tunnel ◽  
Low Speed ◽  
Low Speed Wind Tunnel ◽  
Design And Construction

Numerical and Experimental Study of Turbulent Flows Around Clark Y-14 Aerofoil

2015 ◽  
Author(s):  
Kshitij Vadake ◽  
Jie Cui
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Real World ◽  
Force Measurement ◽  
Test Model ◽  
Wind Tunnel Testing ◽  
Cfd Simulations ◽  
Measurement Device ◽  
Tunnel Testing

Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) have been instrumental in Fluid Mechanics to help solve scientific and engineering problems. This research attempts to use both techniques to perform a parametric study of turbulence flow around airfoil ClarkY-14 at various velocity and angle of attack (AoA). Clark Y-14 airfoil was designed in the 1920’s. It demonstrated good overall performance at low and moderate Reynolds numbers. With the progress in the aviation field, its performance was sub-optimal for newer aircraft designs. However, with the advent of RC airplanes and model aircrafts, there is a renewed interest in this airfoil. Various research projects have been conducted using this airfoil, but there hasn’t been a combined EFD and CFD study of the performance characteristics of the airfoil itself, which still finds real world applications today. One important aspect of this research included the investigation of the effects of a Force Measurement Device/Sensor, which is typically used in scaled/full-size wind tunnels to mount the test model as well as measure the forces/moments acting on it during the testing. The presence of such a device could affect the quality of the data obtained from the wind tunnel testing when compared to a real world application scenario where the aforementioned device may not be present. To the best of the author’s knowledge, no detailed study has been published on the effects of such devices. In this study, the results with and without the measuring device were generated by using CFD simulations. The results were then compared to see to what extent the inclusion of these devices will affect the results. The methodology used for this research was experimental as well as computational. In the present research, a commercially available CFD software STAR-CCM+ was employed to simulate the flows around airfoil Clark Y-14. The experimental data was obtained from wind tunnel tests using AEROLAB Educational Wind Tunnel (EWT) and compared with the simulation data from the CFD. The two data sets were in good agreement. Both experimental and simulation results were used to understand the effects of the measurement device/sensor used in the scaled wind tunnel on the lift and drag coefficients of the airfoil. Two separate CFD simulation setups were designed to model the presence and absence of the measurement device/sensor. These setups replicated the wind tunnel setup. The airfoil was tested and simulated at different speeds as well as different AoA. The comparative study gave a useful insight on the accuracy of the CFD simulations in relation to the actual testing. The analysis of results concluded that the force measurement device/sensor had insignificant effects on the accuracy and quality of data collected through wind tunnel testing.

Wind tunnel investigation on the retention of air pollutants in three-dimensional recirculation zones in urban areas

2007 ◽  
Vol 41 (23) ◽  
pp. 4949-4961 ◽  
Author(s):  
Marcos Sebastião de Paula Gomes ◽  
André Augusto Isnard ◽  
José Maurício do Carmo Pinto
Keyword(s):  
Wind Tunnel ◽  
Urban Areas ◽  
Air Pollutants ◽  
Three Dimensional ◽  
Recirculation Zones

Solution of Levi Civita’s Problem by Infinite Matrix Inversion

1973 ◽  
Vol 40 (1) ◽  
pp. 31-36 ◽  
Author(s):  
M. Bentwich
Keyword(s):  
Flow Pattern ◽  
Flow Direction ◽  
Leading Edge ◽  
Arbitrary Cross Section ◽  
Matrix Inversion ◽  
Infinite Matrix ◽  
Algebraic Equations ◽  
Flow Past ◽  
Linear Algebraic Equations ◽  
Wet Surface

The author proposes a new method by which one can solve for the two-dimensional irrotational fully cavitating flow past a cylinder of arbitrary cross section. Unlike the available solutions, it is in the form of two expansions each valid in part of the complex potential plane w = Φ + iΨ. The a priori unknown coefficients in the two expansions are linked by infinitely many linear algebraic equations. By inverting the associated matrix and utilizing the boundary condition, that represent the geometry of the wet surface, the coefficients in the expansions are evaluated and the solution is completed. Cases in which the wet surface is circular, the pressure along the free streamlines is constant, and the entire flow pattern is symmetric with respect to flow direction at infinity are considered in detail. Also, the well-known solution for the flow past a flat plate is compared to that obtained by the method of matrix inversion. Judging from these results, the convergence of the series appears to be very rapid. The author finally discusses the applicability of the method to cases in which the obstacle has a sharp leading edge, the pressure in the cavity is not uniform, or the flow pattern is not symmetric.

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