Numerical analysis of convection heat transfer from an array of perforated fins using the Reynolds averaged Navier–Stokes equations and large-eddy simulation method

2018 ◽  
Vol 63 ◽  
pp. 660-687 ◽  
Author(s):  
A.H. Dastbelaraki ◽  
M. Yaghoubi ◽  
M. M Tavakol ◽  
A. Rahmatmand
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Stokes Equations ◽  
Convection Heat Transfer ◽  
Simulation Method ◽  
Navier Stokes ◽  
Convection Heat ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Large Eddy

Modeling and analysis of solar air channels with attachments of different shapes

2019 ◽  
Vol 29 (5) ◽  
pp. 1815-1845 ◽  
Author(s):  
Younes Menni ◽  
Ahmed Azzi ◽  
A. Chamkha
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Research Work ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Transfer Coefficients ◽  
Navier Stokes Equations ◽  
Content Type ◽  
Modeling And Analysis ◽  
Air Channels

Purpose This paper aims to report the results of numerical analysis of turbulent fluid flow and forced-convection heat transfer in solar air channels with baffle-type attachments of various shapes. The effect of reconfiguring baffle geometry on the local and average heat transfer coefficients and pressure drop measurements in the whole domain investigated at constant surface temperature condition along the top and bottom channels’ walls is studied by comparing 15 forms of the baffle, which are simple (flat rectangular), triangular, trapezoidal, cascaded rectangular-triangular, diamond, arc, corrugated, +, S, V, double V (or W), Z, T, G and epsilon (or e)-shaped, with the Reynolds number changing from 12,000 to 32,000. Design/methodology/approach The baffled channel flow model is controlled by the Reynolds-averaged Navier–Stokes equations, besides the k-epsilon (or k-e) turbulence model and the energy equation. The finite volume method, by means of commercial computational fluid dynamics software FLUENT is used in this research work. Findings Over the range investigated, the Z-shaped baffle gives a higher thermal enhancement factor than with simple, triangular, trapezoidal, cascaded rectangular-triangular, diamond, arc, corrugated, +, S, V, W, T, G and e-shaped baffles by about 3.569-20.809; 3.696-20.127; 3.916-20.498; 1.834-12.154; 1.758-12.107; 7.272-23.333; 6.509-22.965; 8.917-26.463; 8.257-23.759; 5.513-18.960; 8.331-27.016; 7.520-26.592; 6.452-24.324; and 0.637-17.139 per cent, respectively. Thus, the baffle of Z-geometry is considered as the best modern model of obstacles to significantly improve the dynamic and thermal performance of the turbulent airflow within the solar channel. Originality/value This analysis reports an interesting strategy to enhance thermal transfer in solar air channels by use of attachments with various shapes

A Cartesian Explicit Solver for Complex Hydrodynamic Applications

2014 ◽  
Author(s):  
P. Bigay ◽  
A. Bardin ◽  
G. Oger ◽  
D. Le Touzé
Keyword(s):  
Level Set ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Simulation Method ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Flow Past A Cylinder ◽  
Explicit Solver

In order to efficiently address complex problems in hydrodynamics, the advances in the development of a new method are presented here. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) solver, with a ghost-cell method for geometry handling and a Level-set method for the treatment of biphase-flows. The explicit nature of the solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used. The treatment of arbitrary geometries is addressed in the hyperbolic and viscous framework. Viscous effects are computed via a finite difference computation of viscous fluxes and turbulent effects are addressed via a Large-Eddy Simulation method (LES). The Level-Set solver used to handle biphase flows is also presented. The solver is validated on 2-D test cases (flow past a cylinder, 2-D dam break) and future improvements are discussed.

scholarly journals Computational Analysis of Natural Convection Heat Transfer on a Vertical Plate with Discrete Heat Sources

2020 ◽  
Vol 9 (3) ◽  
pp. 3736-3742
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Vertical Plate ◽  
Stokes Equations ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Heat Sources ◽  
Convection Heat ◽  
Grashof Number ◽  
Discrete Heat Sources

In the present study, buoyancy driven free convection flow along the vertical plate with discrete heat sources is analyzed. To illustrate free convection heat transfer along a vertical plate with finite discrete heat sources a 2-D steady-state model is considered. The thermos-physical properties of fluid are assumed constant except for the buoyancy terms, which are computed using the Boussinesq approximation of Navier-stokes equation. The two-dimensional Navier-stokes equations are solved using SIMPLER algorithm. The dimensionless equations are descretised and solved by using central difference finite difference approach. The development of the air flow caused by buoyancy induced free convective heat transfer has been studied through the progression of velocity and temperature fields. The results are obtained for various Grashof numbers Gr=103 , 104 and 5x 104 , and the influence of Grashof number on flow field has been studied. Average Nusselt number at the plate is also obtained. The effect of variation of Prandtl number at a given Grashof number is also studied.

Numerical and scalability analysis of an unstructured Cartesian flow solver

2011 ◽  
Vol 225 (9) ◽  
pp. 2138-2148 ◽  
Author(s):  
Y H Yau ◽  
A Badarudin ◽  
P A Rubini
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Source Codes ◽  
Scalability Analysis ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Parallel Code

This article describes a systematic approach in building a flow solver for large eddy simulation (LES). Finite volume discretizations of the filtered, incompressible, Navier–Stokes equations were explained. The theory progresses to the description of the step-by-step process (mainly in increasing functionality or capability) in developing a three-dimensional, unstructured Cartesian mesh, parallel code after evaluating numerical factors, and available options carried out earlier. This was followed by a presentation of results produced from the simulations of laminar flow, related to the validation of the source codes, which indicates that the flow solver is behaving satisfactorily.

Large Eddy Simulation of Turbulent-Cavitation Interactions in a Venturi Nozzle

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Nagendra Dittakavi ◽  
Aditya Chunekar ◽  
Steven Frankel
Keyword(s):  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Small Scale ◽  
Navier Stokes Equations ◽  
Vapor Cavity ◽  
Eddy Simulation ◽  
Downstream Region ◽  
Large Eddy ◽  
Venturi Nozzle

Large eddy simulation of turbulent cavitating flow in a venturi nozzle is conducted. The fully compressible Favre-filtered Navier–Stokes equations are coupled with a homogeneous equilibrium cavitation model. The dynamic Smagorinsky subgrid-scale turbulence model is employed to close the filtered nonlinear convection terms. The equations are numerically integrated in the context of a generalized curvilinear coordinate system to facilitate geometric complexities. A sixth-order compact finite difference scheme is employed for the Navier–Stokes equations with the AUSM+-up scheme to handle convective terms in the presence of large density gradients. The stiffness of the system due to the incompressibility of the liquid phase is addressed through an artificial increase in the Mach number. The simulation predicts the formation of a vapor cavity at the venturi throat with an irregular shedding of the small scale vapor structures near the turbulent cavity closure region. The vapor formation at the throat is observed to suppress the velocity fluctuations due to turbulence. The collapse of the vapor structures in the downstream region is a major source of vorticity production, resulting into formation of hair-pin vortices. A detailed analysis of the vorticity transport equation shows a decrease in the vortex-stretching term due to cavitation. A substantial increase in the baroclinic torque is observed in the regions where the vapor structures collapse. A spectra of the pressure fluctuations in the far-field downstream region show an increase in the acoustic noise at high frequencies due to cavitation.

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