scholarly journals Computational Analysis of Fluid Forces on an Obstacle in a Channel Driven Cavity: Viscoplastic Material Based Characteristics

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 529
Author(s):  
Rashid Mahmood ◽  
Afraz Hussain Majeed ◽  
Qurrat ul Ain ◽  
Jan Awrejcewicz ◽  
Imran Siddique ◽  
...  
Keyword(s):  
Computational Grids ◽  
Neumann Condition ◽  
Viscoplastic Material ◽  
Driven Cavity ◽  
Drag And Lift Coefficients ◽  
Fluid Forces ◽  
Bingham Number ◽  
Element Approach ◽  
Drag And Lift ◽  
Velocity Pressure

In the current work, an investigation has been carried out for the Bingham fluid flow in a channel-driven cavity with a square obstacle installed near the inlet. A square cavity is placed in a channel to accomplish the desired results. The flow has been induced using a fully developed parabolic velocity at the inlet and Neumann condition at the outlet, with zero no-slip conditions given to the other boundaries. Three computational grids, C1, C2, and C3, are created by altering the position of an obstacle of square shape in the channel. Fundamental conservation and rheological law for viscoplastic Bingham fluids are enforced in mathematical modeling. Due to the complexity of the representative equations, an effective computing strategy based on the finite element approach is used. At an extra-fine level, a hybrid computational grid is created; a very refined level is used to obtain results with higher accuracy. The solution has been approximated using P2 − P1 elements based on the shape functions of the second and first-order polynomial polynomials. The parametric variables are ornamented against graphical trends. In addition, velocity, pressure plots, and line graphs have been provided for a better physical understanding of the situation Furthermore, the hydrodynamic benchmark quantities such as pressure drop, drag, and lift coefficients are assessed in a tabular manner around the external surface of the obstacle. The research predicts the effects of Bingham number (Bn) on the drag and lift coefficients on all three grids C1, C2, and C3, showing that the drag has lower values on the obstacle in the C2 grid compared with C1 and C3 for all values of Bn. Plug zone dominates in the channel downstream of the obstacle with augmentation in Bn, limiting the shear zone in the vicinity of the obstacle.

scholarly journals Numerical Analysis of Fluid Forces for Flow Past a Square Rod with Detached Dual Control Rods at Various Gap Spacing

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 159
Author(s):  
Raheela Manzoor ◽  
Abdul Ghaffar ◽  
Dumitru Baleanu ◽  
Kottakkaran Sooppy Nisar
Keyword(s):  
Strouhal Number ◽  
Numerical Study ◽  
Control Rod ◽  
Drag And Lift Coefficients ◽  
Fluid Forces ◽  
Flow Past ◽  
Upstream Direction ◽  
Drag And Lift ◽  
Gap Spacing ◽  
Control Rods

A two-dimensional numerical study was conducted for flow past a square rod in the presence of two control rods. One is placed vertically in the upstream direction and the second one is placed horizontally in the downstream direction of the square rod. The influence of gap spacing was studied by taking g1 = 1–5 and g2 = 0.5–5 (where g1 is the gap between the upstream control rod and the main rod, and g2 is the space between the main rod and the downstream control rod) at Re = 160. The simulation results were obtained in the form of vorticity contour, drag and lift coefficients, Strouhal number, and force statistics. Under the effect of gap spacing, three different flow modes were found and named according to their behavior. It was found that the mean drag coefficient showed decreasing behavior by increasing the value of g2 continually at a fixed value of g1. The largest value of C d m e a n was found at (g1, g2) = (1, 1) and the greatest percentage reduction in C d m e a n was obtained at (g1, g2) = (1, 3), which is 139.72%. The effect of thrust was also noticed for all selected values of g1 and g2. Furthermore, it was noticed that the Strouhal number and the root mean square values of the drag and lift coefficients smaller values than the single rod values, except for the Clrms value of (g1, g2) = (1, 3) and (1, 4).

scholarly journals Topological Characteristics of Obstacles and Nonlinear Rheological Fluid Flow in Presence of Insulated Fins: A Fluid Force Reduction Study

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Afraz Hussain Majeed ◽  
Fahd Jarad ◽  
Rashid Mahmood ◽  
Imran Saddique
Keyword(s):  
Fluid Flow ◽  
Power Law ◽  
Nonlinear Flow ◽  
Cross Sectional ◽  
Fluid Forces ◽  
Bingham Number ◽  
Drag Forces ◽  
Force Reduction ◽  
Drag And Lift ◽  
Element Technique

In this work, a comprehensive study of fluid forces and thermal analysis of two-dimensional, laminar, and incompressible complex (power law, Bingham, and Herschel–Bulkley) fluid flow over a topological cross-sectional cylinder (square, hexagon, and circle) in channel have been computationally done by using finite element technique. The characteristics of nonlinear flow for varying ranges of power law index 0.4 ≤ n ≤ 1.6 , Bingham number 0 ≤ Bn ≤ 50 , Prandtl number 0.7 ≤ Pr ≤ 10 , Reynolds number 10 ≤ Re ≤ 50 , and Grashof number 1 ≤ Gr ≤ 10   have been examined. Considerable evaluation for thermal flow field in the form of dimensionless velocity profile, isotherms, drag and lift coefficients, and average Nusselt number Nu avg is done. Also, for a range of Bn , the drag forces reduction is observed for circular and hexagonal obstacles in comparison with the square cylinder. At Bn = 0   corresponding to Newtonian fluid, maximum reduction in drag force is reported.

Flow features of three side-by-side rectangular cylinders under the effect of aspect ratios and Reynolds numbers

2020 ◽  
pp. 2150034
Author(s):  
Hamid Rahman ◽  
Waqas Sarwar Abbasi ◽  
Shams-ul-Islam ◽  
Raees Khan ◽  
Muhammad Uzair Khan
Keyword(s):  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Physical Parameters ◽  
Drag And Lift Coefficients ◽  
Fluid Forces ◽  
Aspect Ratios ◽  
Flow Features ◽  
Drag And Lift ◽  
Boltzmann Method ◽  
Rectangular Cylinders

This study focuses on the characteristics of flow past three side-by-side rectangular cylinders under the effect of aspect ratios (AR) and Reynolds numbers (Re) at two different gap ratios ([Formula: see text]) using the lattice Boltzmann method. For this purpose, AR is varied in the range of 0.25–4, the Re values are 100, 140 and 180 and the two different values of [Formula: see text] taken into account are [Formula: see text] and 3. The results are presented in the form of vorticity contours, temporal histories of drag and lift coefficients and power spectrum of lift coefficients. Also, the variation of physical parameters like mean drag coefficient, Strouhal number and the root-mean-square values of drag and lift coefficients with Re and AR is presented for [Formula: see text] and 3. The current numerical computations yield that for both gap ratios and all Re, there exist four different flow regimes depending on AR: (a) steady flow, (b) modulated flow, (c) symmetric flow and (d) periodic flow. At narrow gap ratios, the jet flow emerging within the gaps of cylinders altered the flow structures and fluid forces abruptly. The aspect ratio is found to have more influence on the flow characteristics of cylinders as compared to the Reynolds numbers at large gap ratios.

Simplified Aerodynamic Loading Model for Non-Production Conditions for Floating Wind Systems Design

2021 ◽  
Author(s):  
Armando Alexandre ◽  
Raffaello Antonutti ◽  
Theo Gentils ◽  
Laurent Mutricy ◽  
Pierre Weyne
Keyword(s):  
Wind Speed ◽  
Coupled Model ◽  
Systems Design ◽  
Simplified Model ◽  
Aerodynamic Loads ◽  
Drag And Lift Coefficients ◽  
Aerodynamic Loading ◽  
Yaw Bearing ◽  
Drag And Lift ◽  
Turbine Model

Abstract Floating wind is now entering a commercial-stage, and there are a significant number of commercial projects in countries like France, Japan, UK and Portugal. A floating wind project is complex and has many interdependencies and interfaces. During all stages of the project several participants are expected to use a numerical model of the whole system and not only the part the participant has to design. Examples of this are the mooring and floater designer requiring a coupled model of the whole system including also the wind turbine, the operations team requiring a model of the system to plan towing and operations. All these stakeholders require a coupled model where the hydrodynamics, aerodynamics and structural physics of the system are captured with different levels of accuracy. In this paper, we will concentrate on a simplified model for the aerodynamic loading of the turbine in idling and standstill conditions that can be easily implemented in a simulation tool used for floater, mooring and marine operations studies. The method consists of using a subset of simulations at constant wind speed (ideally close to the wind speed required for the simulations) run on a detailed turbine model on a rigid tower and fixed foundation — normally run by the turbine designer. A proxy to the aerodynamic loads on the rotor and nacelle (RNA) is to take the horizontal yaw bearing loads. The process is then repeated for a range of nacelle yaw misalignments (for example every 15° for 360°). A look-up table with the horizontal yaw bearing load for the range of wind-rotor misalignments investigated is created. The simplified model of the aerodynamic loads on the RNA consists of a fixed blade (or wing) segment located at the hub, where aerodynamic drag and lift coefficients can be specified. Using the look-up tables created using the detailed turbine model, drag and lift coefficients are estimated as a function of the angle between the rotor and the wind direction. This representation of the aerodynamic loading on the RNA was then verified against full-field turbulent wind simulations in fixed and floating conditions using a multi-megawatt commercial turbine. The results for the parameters concerning the floater, mooring and marine operations design were monitored (e.g. tower bottom loads, offsets, pitch, mooring tensions) for extreme conditions and the errors introduced by this simplified rotor are generally lower than 4%. This illustrates that this simplified representation of the turbine can be used by the various parties of the project during the early stages of the design, particularly when knowing the loading within the RNA and on higher sections of the tower is not important.

Vibration Excitation Forces in a Normal Triangular Tube Bundle Subjected to Two-Phase Cross Flow

2011 ◽  
Author(s):  
E. S. Perrot ◽  
N. W. Mureithi ◽  
M. J. Pettigrew ◽  
G. Ricciardi
Keyword(s):  
Tube Bundle ◽  
Cross Flow ◽  
Random Excitation ◽  
Two Phase ◽  
Constant Frequency ◽  
Fluid Forces ◽  
Drag Forces ◽  
Wide Range ◽  
Drag And Lift ◽  
Lift And Drag

This paper presents test results of vibration forces in a normal triangular tube bundle subjected to air-water cross-flow. The dynamic lift and drag forces were measured with strain gage instrumented cylinders. The array has a pitch-to-diameter ratio of 1.5, and the tube diameter is 38 mm. A wide range of void fraction and fluid velocities were tested. The experiments revealed significant forces in both the drag and lift directions. Constant frequency and quasi-periodic fluid forces were found in addition to random excitation. These forces were analyzed and characterized to understand their origins. The forces were found to be dependent on the position of the cylinder within the bundle. The results are compared with those obtained with flexible cylinders in the same tube bundle and to those for a rotated triangular tube bundle. These comparisons reveal the influence of quasi-periodic forces on tube motions.

Thermally driven cavity flow with Neumann condition for the pressure

2002 ◽  
Vol 40 (1-2) ◽  
pp. 327-336 ◽  
Author(s):  
Obidio Rubio ◽  
Elba Bravo ◽  
Julio R. Claeyssen
Keyword(s):  
Cavity Flow ◽  
Neumann Condition ◽  
Driven Cavity ◽  
Thermally Driven ◽  
Driven Cavity Flow

Research on Aerodynamic Characteristics of a Simplified SUV Model

2013 ◽  
Vol 275-277 ◽  
pp. 603-606 ◽  
Author(s):  
Xing Jun Hu ◽  
Lei Liao ◽  
Jing Yu Wang ◽  
Li Min Fu
Keyword(s):  
Drag Coefficient ◽  
Pressure Distribution ◽  
Aerodynamic Characteristics ◽  
Drag And Lift Coefficients ◽  
Transition Radius ◽  
Drag And Lift ◽  
Underbody Diffuser

The aerodynamics characteristics of square Mira model were researched by simulation, the drag coefficient and the aerodynamic characteristics around model were achieved with analysis of velocity and pressure distribution. Based on results, the angle of rear wind window, the angle of underbody diffuser and the front transition radius were changed, the drag and lift coefficients were achieved. The conclusions provide reference for how to reduce drag coefficient of SUV

scholarly journals Numerical Simulation of Flow Control around a Circular Cylinder by Installing a Wedge-Shaped Device Upstream

2019 ◽  
Vol 7 (12) ◽  
pp. 422 ◽  
Author(s):  
Xiaoshuang Han ◽  
Jie Wang ◽  
Bo Zhou ◽  
Guiyong Zhang ◽  
Soon-Keat Tan
Keyword(s):  
Circular Cylinder ◽  
Cavity Mode ◽  
Wake Flow ◽  
Side Length ◽  
Length Ratio ◽  
Drag And Lift Coefficients ◽  
Spacing Ratio ◽  
Wake Patterns ◽  
Drag And Lift ◽  
Sudden Jump

The effect of a triangular wedge upstream of a circular cylinder has been investigated, and the findings are presented herein. The triangular wedge is equilateral in plan form, and the Reynolds number based on the diameter of the main cylinder is approximately 200. Contours of vorticity clearly show that two entirely different wake patterns exist between the wedge and the main cylinder. There also exists a critical spacing ratio and side length ratio at which the wake flow pattern shifts from one within the cavity mode to one within the wake impingement mode. For a relatively small side length ratio of l w / D = 0.20 and 0.27, where the side length refers to the length of one side of the triangular wedge, the drag and lift coefficients decrease monotonically with the spacing ratio. There is a sudden jump of the drag and lift coefficients at larger side length ratios of l w / D = 0.33 and 0.40. This study shows that at a spacing ratio of L/D = 2.8 (where L is the distance between the vertex of the wedge and the center of the cylinder) and a wedge side length of l w / D = 0.40, the reduction of the amplitude of lift and mean drag coefficient on the main cylinder are 71.9% and 60.1%, respectively.

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