Flow and deposition characteristics of nanoparticles in a 90° square bend

Bouzit

2020

3D computational analyses are achieved to predict seriously the influences of thermal buoyancy strength and Dean number on Dean vortices, flow behavior and the rate heat transfer through 180° curved channel of square cross-sectional form. The work shows many results, so this paper emphasizes only on the results of 60° cross-sectional position of the bend duct. The principal partial equations of continuity, momentum and energy are considering in three dimensions under the following assumptions: flow is incompressible and laminar, and it is solved in steady-state. The aforementioned equations are subjected to suitable boundary conditions under following range as: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at fixed value of Prandtl number Pr = 1. The principal results of this work are illustrated as streamline and isotherm contours to draw to flow patterns and temperature distributions respectively. The axial velocity profile is shown versus above conditions, the local Nusselt number is also presented along the wall of 60° cross-sectional position. The results show that the thermal buoyancy can balance the effect of centrifugal force of fluid particles at the angular position of 60°.

Section: Introductionmentioning

confidence: 99%

Computational Analyses of Flow and Heat Transfer at 60° Position of 180° Curved Duct of Square Cross-Section

Bouzit

2020

“…( ) cross section area wetted perimeter (2) From the Dean number expression, it is evident that the instability of flow through a curved duct depends on large number of fluid parameters and geometrical configurations such as the kind of fluid (Newtonian or non-Newtonian) [3][4][5], the duct cross-sectional form (circular [2], triangular [6], square [7][8], elliptical [9]), the value of curvature radius [10] and finally the external forces exerted on the flow as electromagnetic force [11]. For example the investigation of Dean [2] that is carried out for curved channel of circular cross-section showed that above the critical value of Dean number, new kind of counter-rotating vortices (pair) are observed to appeared on outer wall of duct.…”

Section: Introductionmentioning

confidence: 99%

3D Simulation of Incompressible Poiseuille Flow through 180° Curved Duct of Square Cross-section under Effect of Thermal Buoyancy

Period. Polytech. Mech. Eng.

Makinde

et al. 2019

In this paper, three-dimensional numerical simulations are carried out to investigate and analyze the gradual effects of thermal buoyancy strength on laminar flow of an incompressible viscous fluid and heat transfer rate inside a 180° curved channel of square cross-section. The governing equations of continuity, momentum and energy balance are obtained and solved numerically using finite volume method. The effect of Dean number, De, and Richardson number, Ri, on dimensionless velocity profiles and Nusselt number are examined for the conditions: De = 125 to 150, Ri = 0 to 2 at Pr = 1. The mean results are illustrated in terms of streamline and isotherm contours to interpret the flow behaviors and its effect on heat transfer rate. Dimensionless velocity profiles and the local Nusselt number at the angle 0° and 90° are presented and discussed. Also, the average Nusselt number on surfaces of curved duct is computed. The obtained results showed that by adding thermal buoyancy to computed domain, some early Dean vortices are observed at the angle 0° and new sort are observed at 90°. Furthermore, increase in Dean number increases the heat transfer rate. In other hand, increase in Richardson number decreases the average Nusselt number of 180° curved duct.

“…The Dean number shows that the dean vortex size depends on many fluidic parameters as well as geometrical configurations. Examples including: the type fluid (Newtonian or non-Newtonian) [3][4][5], the form of duct cross-section (circular [2], triangular [6], square [7][8], elliptical [9]), the value of curvature radius [10] and the external force acting on the fluid flow as electromagnetic force [11].…”

Section: Introductionmentioning

confidence: 99%

3D Simulation of Dean Vortices at 30° Position of 180° Curved Duct of Square Cross-Section under Opposing Buoyancy

Bouzit

2018

DDF

3D numerical simulations are performed to analyze correctly the effect of opposing thermal buoyancy and Dean number on Dean vortices, fluid flow and heat transfer through 180° curved duct of square cross-section. Due to tremendous found results, this works emphasizes only at the position 30° of the bend portion. The governing equations involving momentum, continuity and energy are solved in three dimensions under these assumptions: the flow is laminar, steady-state and incompressible. The present study is investigated in the range of these conditions: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at Pr = 1. The principal obtained results are represented in forms of streamlines and isotherms to analyze and to discuss the found physical phenomena. The local Nusselt number along the wall of square cross-section is also computed and presented. The main found point is that the opposing thermal buoyancy has a tendency to eliminate the effect of centrifugal force at the position 30° of bend portion of 180° curved duct.