Reduction of Unsteady Forces on Bluff Bodies Using Rotating Control Cylinders

1999 ◽  
pp. 279-284
Author(s):  
Sanjay Mittal
Keyword(s):  
Bluff Bodies ◽  
Unsteady Forces

CFD Study of the Pressure Distribution on the Back of a 3-D Bluff Body (CUBE) of Air Flow in Different Reynolds Numbers

2009 ◽  
Author(s):  
Mohammad Javad Izadi ◽  
Pegah Asghari ◽  
Malihe Kamkar Delakeh
Keyword(s):  
Reynolds Number ◽  
Bluff Body ◽  
Free Stream ◽  
Fluid Flows ◽  
Reynolds Numbers ◽  
The Body ◽  
Stream Velocity ◽  
Bluff Bodies ◽  
Unsteady Forces ◽  
Flow Round

The study of flow around bluff bodies is important, and has many applications in industry. Up to now, a few numerical studies have been done in this field. In this research a turbulent unsteady flow round a cube is simulated numerically. The LES method is used to simulate the turbulent flow around the cube since this method is more accurate to model time-depended flows than other numerical methods. When the air as an ideal fluid flows over the cube, flow separate from the back of the body and unsteady vortices appears, causing a large wake behind the cube. The Near-Wake (wake close to the body) plays an important role in determining the steady and unsteady forces on the body. In this study, to see the effect of the free stream velocity on the surface pressure behind the body, the Reynolds number is varied from one to four million and the pressure on the back of the cube is calculated numerically. From the results of this study, it can be seen that as the velocity or the Reynolds number increased, the pressure on the surface behind the cube decreased, but the rate of this decrease, increased as the free stream flow velocity increased. For high free stream velocities the base pressure did not change as much and therefore the base drag coefficient stayed constant (around 1.0).

scholarly journals Theoretical and testing investigation of wind–rain coupling loads on some typical bluff bodies

2018 ◽  
Vol 22 (1) ◽  
pp. 156-171 ◽  
Author(s):  
Ying Chang ◽  
Lin Zhao ◽  
Yaojun Ge
Keyword(s):  
Wind Tunnel ◽  
Probability Distribution ◽  
Cross Sections ◽  
Joint Probability ◽  
Joint Probability Distribution ◽  
Bluff Bodies ◽  
Copula Functions ◽  
Unsteady Forces ◽  
Scale Models ◽  
Unsteady Force

The article presents a mathematical theoretical framework and fitting parameters with aspects of joint probability distribution of wind and rain, separate wind and rain action, and coupled wind and rain effects on steady and unsteady forces acting on some typical bluff bodies. Gumbel and copula functions were first selected to describe the joint probability distribution of wind speed and rain intensity. Then, two models, a raindrop impact model and an equivalent air density model, were adopted to quantify the loading action considering only separate wind and rain action, and simplified coupled effects with superimposition of wind and rain show that it would be accurate enough to neglect separated rain influence in steady wind and rain loading conditions. Furthermore, wind tunnel testing has been carried out under coupled wind and rain conditions with the help of a high-precision raining simulation system in TJ-1 wind tunnel on various reduced-scale models with some typical cross sections, such as circular and rectangular, thin plate, and streamlined box, and their aerodynamic loading and wind–rain-induced performance have been systematically compared. It has thus been found that the coupling effects of wind and rain should not be neglected in steady and unsteady force models.

Fundamental Control of Wake Behind Bluff Bodies : A Review

2012 ◽  
Vol 2 (8) ◽  
pp. 134-135
Author(s):  
Dalbir Singh Dalbir Singh ◽  
◽  
M.M. Gaud M.M. Gaud ◽  
Jaswinder Singh Jaswinder Singh
Keyword(s):  
Bluff Bodies

scholarly journals Data-driven RANS closures for three-dimensional flows around bluff bodies

2021 ◽  
pp. 104997
Author(s):  
Jasper P. Huijing ◽  
Richard P. Dwight ◽  
Martin Schmelzer
Keyword(s):  
Three Dimensional ◽  
Data Driven ◽  
Bluff Bodies

Dynamical control for capturing vortices near bluff bodies

1998 ◽  
Vol 58 (2) ◽  
pp. 1883-1898 ◽  
Author(s):  
Áron Péntek ◽  
James B. Kadtke ◽  
Gianni Pedrizzetti
Keyword(s):  
Bluff Bodies ◽  
Dynamical Control

Formation of Vortex Street in Laminar Boundary Layer

1980 ◽  
Vol 47 (2) ◽  
pp. 227-233 ◽  
Author(s):  
M. Kiya ◽  
M. Arie
Keyword(s):  
Boundary Layer ◽  
Shear Flow ◽  
Laminar Boundary Layer ◽  
Solid Wall ◽  
Vortex Sheet ◽  
Vortex Street ◽  
Bluff Bodies ◽  
Uniform Shear ◽  
Uniform Shear Flow ◽  
Vortex Patterns

Main features of the formation of vortex street from free shear layers emanating from two-dimensional bluff bodies placed in uniform shear flow which is a model of a laminar boundary layer along a solid wall. This problem is concerned with the mechanism governing transition induced by small bluff bodies suspended in a laminar boundary layer. Calculations show that the background vorticity of shear flow promotes the rolling up of the vortex sheet of the same sign whereas it decelerates that of the vortex sheet of the opposite sign. The steady configuration of the conventional Karman vortex street is not possible in shear flow. Theoretical vortex patterns are experimentally examined by a flow-visualization technique.

Laminar Fluid Flow Around Two Wall-Mounted Blocks of Different Size

2009 ◽  
Author(s):  
Mohammad Mehdi Tavakol ◽  
Mohammad Eslami
Keyword(s):  
Fluid Flow ◽  
Free Stream ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Bluff Bodies ◽  
Wake Region ◽  
Science And Engineering ◽  
Vortical Structures ◽  
Laminar Fluid Flow ◽  
Pressure Distributions

Fluid flow around single or multiple bluff bodies mounted on a surface has great significance in science and engineering. Understanding the characteristics of different vortices formed around wall-mounted bodies is quite necessary for different applications. Although the case of a single surface mounted cube has been studied extensively, only little attention has been paid to the flow around two or more rectangular blocks in array. Therefore, a CFD code is developed to calculate three dimensional steady state laminar fluid flow around two cuboids of arbitrary size and configuration mounted on a surface in free stream conditions. The employed numerical scheme is finite volume and SIMPLE algorithm is used to treat pressure and velocity coupling. Results are presented for two rectangular blocks of the different size mounted on a surface in various inline arrangements. Streamlines are plotted for blocks of different size ratio. Velocity and pressure distributions are also plotted in the wake region behind the obstacles. It is shown that how the behavior of flow field and vortical structures depend on the respective size and location of the larger block in comparison with the case of two inline wall mounted cubes of the same size.

scholarly journals Unsteady forces on a circular cylinder at critical Reynolds numbers

2014 ◽  
Vol 26 (12) ◽  
pp. 125110 ◽  
Author(s):  
O. Lehmkuhl ◽  
I. Rodríguez ◽  
R. Borrell ◽  
J. Chiva ◽  
A. Oliva
Keyword(s):  
Circular Cylinder ◽  
Reynolds Numbers ◽  
Unsteady Forces ◽  
Critical Reynolds Numbers
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