Effects of Temperature, Salinity, and Fluid Type on Acoustic Characteristics of Turbulent Flow Around Circular Cylinder

Author(s):  
Sertaç Bulut ◽  
Selma Ergin
2018 ◽  
Vol 28 (9) ◽  
pp. 2189-2207 ◽  
Author(s):  
Erman Ulker ◽  
Sıla Ovgu Korkut ◽  
Mehmet Sorgun

Purpose The purpose of this paper is to solve Navier–Stokes equations including the effects of temperature and inner pipe rotation for fully developed turbulent flow in eccentric annuli by using finite difference scheme with fixing non-linear terms. Design/methodology/approach A mathematical model is proposed for fully developed turbulent flow including the effects of temperature and inner pipe rotation in eccentric annuli. Obtained equation is solved numerically via central difference approximation. In this process, the non-linear term is frozen. In so doing, the non-linear equation can be considered as a linear one. Findings The convergence analysis is studied before using the method to the proposed momentum equation. It reflects that the method approaches to the exact solution of the equation. The numerical solution of the mathematical model shows that pressure gradient can be predicted with a good accuracy when it is compared with experimental data collected from experiments conducted at Izmir Katip Celebi University Flow Loop. Originality/value The originality of this work is that Navier–Stokes equations including temperature and inner pipe rotation effects for fully developed turbulent flow in eccentric annuli are solved numerically by a finite difference method with frozen non-linear terms.


1970 ◽  
Vol 4 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Md Mahbubar Rahman ◽  
Md. Mashud Karim ◽  
Md Abdul Alim

The dynamic characteristics of the pressure and velocity fields of unsteady incompressible laminar and turbulent wakes behind a circular cylinder are investigated numerically and analyzed physically. The governing equations, written in the velocity pressure formulation are solved using 2-D finite volume method. The initial mechanism for vortex shedding is demonstrated and unsteady body forces are evaluated. The turbulent flow for Re = 1000 & 3900 are simulated using k-? standard, k-? Realizable and k-? SST turbulence models. The capabilities of these turbulence models to compute lift and drag coefficients are also verified. The frequencies of the drag and lift oscillations obtained theoretically agree well with the experimental results. The pressure and drag coefficients for different Reynolds numbers were also computed and compared with experimental and other numerical results. Due to faster convergence, 2-D finite volume method is found very much prospective for turbulent flow as well as laminar flow.Keywords: Viscous unsteady flow, laminar & turbulent flow, finite volume method, circular cylinder.DOI: 10.3329/jname.v4i1.914Journal of Naval Architecture and Marine Engineering 4(2007) 27-42


2011 ◽  
Vol 66 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Selin Aradag ◽  
Stefan Siegel ◽  
Jürgen Seidel ◽  
Kelly Cohen ◽  
Thomas McLaughlin

2020 ◽  
Vol 92 (7) ◽  
pp. 1001-1017
Author(s):  
Mohammad Reza Saffarian ◽  
Farzad Jamaati ◽  
Amin Mohammadi ◽  
Fatemeh Gholami Malekabad ◽  
Kasra Ayoubi Ayoubloo

Purpose This study aims to evaluate the amount of entropy generation around the NACA 0012 airfoil. This study takes place in four angles of attack of 0°, 5°, 10° and 16° and turbulent regime. Also, the variation in the amount of generated entropy by the changes in temperature and Mach number is investigated. Design/methodology/approach The governing equations are solved using computational fluid dynamics techniques. The continuity, momentum and energy equations and the equations of the SST k-ω turbulence model are solved. The entropy generation at different angles of attack is calculated and compared. The effect of various parameters in the generation of entropy is presented. Findings Results show that the major part of the entropy generation is at the tip of the airfoil. Also, increasing the angle of attack will increase the entropy generation. Also, results show that with increasing the temperature of air colliding with the airfoil, the production of entropy decreases. Originality/value Entropy generation is investigated in the NACA 0012 airfoil at various angles of attack and turbulent flow using the SST turbulence model. Also, the effects of temperature and Mach number on the entropy generation are investigated.


2019 ◽  
Vol 9 (17) ◽  
pp. 3595 ◽  
Author(s):  
Jianfeng Yao ◽  
Wenjuan Lou ◽  
Guohui Shen ◽  
Yong Guo ◽  
Yuelong Xing

To study the influence of turbulence on the wind pressure and aerodynamic behavior of smooth circular cylinders, wind tunnel tests of a circular cylinder based on wind pressure testing were conducted for different wind speeds and turbulent flows. The tests obtained the characteristic parameters of mean wind pressure coefficient distribution, drag coefficient, lift coefficient and correlation of wind pressure for different turbulence intensities and of Reynolds numbers. These results were also compared with those obtained by previous researchers. The results show that the minimum drag coefficient in the turbulent flow is basically constant at approximate 0.4 and is not affected by the turbulence intensity. When the Reynolds number is in the critical regime, the lift coefficient increased sharply to 0.76 in the smooth flow, indicating that flow separation has an asymmetry; however, the asymmetry does not appear in the turbulent flow. Drag coefficient decreases sharply at a lower critical Reynolds number in the turbulent flow than in the smooth flow. In the smooth flow, the separation point is about 80° in the subcritical regime; it suddenly moves backwards in the critical regime and remains almost unchanged at about 140° in the supercritical regime. However, the angular position of the separation point will always be about 140° for turbulent flow for the Reynolds number in these three regimes. Turbulence intensity and Reynolds number have a significant effect on the correlation of wind pressures around the circular cylinder. Turbulence will weaken the positive correlation of the same side and also reduce the negative correlation between the two sides of the circular cylinder.


2018 ◽  
Vol 974 ◽  
pp. 012011 ◽  
Author(s):  
Amirul Hakam ◽  
Basuki Widodo ◽  
Tri Yogi Yuwono ◽  
Chairul Imron

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