AUTHOR=Ain Qurrat Ul , Khan Y. , Mahmood Rashid , Alameer A. , Majeed Afraz Hussain , Faraz N. 

TITLE=Passive Control of Hydrodynamic Forces on a Circular Obstacle in a Transient Flow: FEM Computations

JOURNAL=Frontiers in Physics

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.928087

DOI=10.3389/fphy.2022.928087

ISSN=2296-424X

ABSTRACT=<p>Hydrodynamic forces are crucial in engineering applications; therefore, various research initiatives have been conducted to limit them. In this research, a passive control technique to investigate the fluid forces acting on a circular cylinder in a laminar flow regime is studied. The reliability of the usage of a splitter plate (passive control device) downstream of the obstacle in suppressing the fluid forces on a circular obstacle of diameter <inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>D</mml:mi><mml:mo>=</mml:mo><mml:mn mathvariant="italic">0.1</mml:mn></mml:mrow></mml:math></inline-formula> is presented. The first parameter of the current study is the attachment of splitter plates of various lengths <inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mi>L</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:math></inline-formula>with the obstacle, whereas the gap separation <inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mi>G</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:math></inline-formula> between the splitter plate and the obstacle is used as a second parameter. The control element of the first and second parameters are varied from <inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.1</mml:mn></mml:mrow></mml:math></inline-formula> to <inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.3</mml:mn></mml:mrow></mml:math></inline-formula>. For the attached splitter plates of lengths <inline-formula id="inf6"><mml:math id="m6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.2</mml:mn></mml:mrow></mml:math></inline-formula> and <inline-formula id="inf7"><mml:math id="m7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.3</mml:mn></mml:mrow></mml:math></inline-formula>, the oscillatory behavior of transient flow at <inline-formula id="inf8"><mml:math id="m8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>R</mml:mi><mml:mi>e</mml:mi><mml:mo>=</mml:mo><mml:mn mathvariant="italic">100</mml:mn></mml:mrow></mml:math></inline-formula> is successfully controlled. For the gap separations <inline-formula id="inf9"><mml:math id="m9" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.1</mml:mn></mml:mrow></mml:math></inline-formula> and <inline-formula id="inf10"><mml:math id="m10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn mathvariant="italic">0.2</mml:mn></mml:mrow></mml:math></inline-formula>, the suppression of vortex shedding is also observed. However, it is observed that a splitter plate of too short length and a plate located at an inappropriate gap from an obstacle are worthless. Moreover, the present study is extended for power-law fluid in the same domain, and maximum drag reduction is achieved using the same strategy as for Newtonian fluid. The finite element method is utilized as a computational strategy for complicated nonlinear governing equations. For a clear physical depiction of the problem, velocity and pressure plots have been provided. It is concluded that the presence of a splitter plate has suppressed the vortex shedding and the flow regime turns out to be steady, as is evident from the nonoscillatory drag and lift coefficients.</p>