Free convective of a linear heterogeneous liquid in a square cavity at side heating

2020 ◽  
pp. 108-116
Author(s):  
K.V. Moiseev ◽  
◽  
V.S. Kuleshov ◽  
R.N. Bakhtizin ◽  
◽  
...  
Keyword(s):  
Control Volume ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Double Diffusion ◽  
Boussinesq Approximation ◽  
Square Cavity ◽  
Cell Height ◽  
Volume Method ◽  
Dimensional Statement ◽  
Stratified Liquid

In this work the problem of free convection of the Newtonian poorly stratified liquid in the cell warmed up from left and cooled from right with the heat-insulated horizontal boarders is presented. Liquid with small concentration of salt and initial linear stratification on cell height is considered. The model of double diffusion in a Boussinesq approximation is applied to model the process. The problem is solved both in two - and three-dimensional statement by means of a control volume method and a SIMPLE algorithm. It is shown that vortex structures at the layered mode of convection have quasi-two-dimensional character.

Buoyancy Effect on Developing Turbulent Flow and Heat Transfer in a Helical Pipe With Finite Pitch

2000 ◽  
Author(s):  
B. Zheng ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Control Volume ◽  
Three Dimensional ◽  
Boussinesq Approximation ◽  
Buoyancy Effect ◽  
Constant Wall Temperature ◽  
Flow And Heat Transfer ◽  
Helical Pipe ◽  
Volume Method

Abstract Numerical modeling was performed to investigate the buoyancy effect on developing turbulent flow and the heat transfer characteristics of saturated water in a helical pipe with finite pitch. The renormalization group (RNG) κ–ε model was used to account for the turbulent flow and heat transfer in the helical pipe at a constant wall temperature with or without buoyancy force effect. A control volume method with second-order accuracy was used to numerically solve the three-dimensional full elliptic governing equations for this problem. The O-type nonuniform structured grid system was adopted to discretize the computation domain. The Boussinesq approximation was applied to deal with the buoyancy. This study explored the influence of buoyancy on the developing heat transfer along the helical pipe. Based on the results of this research, the velocity, temperature, and Nusselt number are presented graphically and analyzed.

Effect of Thermal Conductivity Ratio on Laminar Double-Diffusive Free Convection in a Porous Cavity

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Paulo H. S. Carvalho ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Free Convection ◽  
Thermal Equilibrium ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Conductivity Ratio ◽  
Control Volume Method ◽  
Algebraic Equations ◽  
Square Cavity ◽  
Volume Method ◽  
Double Diffusive

This work presents a study on double-diffusive free convection in a porous square cavity using the thermal equilibrium model. Transport equations are discretized using the control-volume method, and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effect of ks/kf on average Nusselt and Sherwood values was investigated. Results show that increasing ks/kf affects Nuw and Shw boosting mass transfer at the expense of reducing overall heat transport across the enclosure.

Turbulent Double-Diffusive Free Convection in a Porous Square Cavity Simulated With the Two Temperature Approach

2016 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Solid Phase ◽  
Control Volume ◽  
Chemical Species ◽  
Simple Algorithm ◽  
Fluid Phase ◽  
Solid Matrix ◽  
Thermal Conductivity Ratio ◽  
Algebraic Equations ◽  
Square Cavity ◽  
Volume Method

This work investigates the influence of thermal conductivity ratio on energy and mass transport across a porous square cavity. Modeling of heat transfer from side to side of the enclosure assumed the hypothesis of thermal non-equilibrium between the solid matrix and the fluid phase. Transport equations were discretized using the control-volume method and the system of algebraic equations obtained was relaxed via the SIMPLE algorithm. Results showed that Shw, mass flux of chemical species and heat flux in the solid phase are strongly dependent of ks/kf, significantly increasing their values as such ratio increases.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

A Thermo-Mechanical Model for a Counterflow Biomass Gasifier

2014 ◽  
Vol 354 ◽  
pp. 227-235
Author(s):  
Marcelo J.S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Capacity ◽  
Macroscopic Model ◽  
Algebraic Equations ◽  
Medium Permeability ◽  
Mechanical Approach ◽  
Volume Method

This article presents a thermo-mechanical approach to investigate heat transfer between solid and fluid phases in a model gasifier. A two-temperature equation approach is applied in addition to a macroscopic model for laminar flow through a porous moving bed. Transport equations are discretized using the control-volume method and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effects on inter-phase heat transfer due to variation of medium permeability, thermal conductivity and thermal capacity are analyzed. Results indicate that for smaller medium permeabilities, as well as for higher solid-to-fluid thermal capacity and thermal conductivity ratios, enhancement of heat transfer between phases is observed.

Numerical Simulation of Laminar Confined Impinging Jet in a Composite Channel

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Local Distribution ◽  
Governing Equations ◽  
Stagnation Region ◽  
Volume Method ◽  
Material Porosity ◽  
Macroscopic Equations

This work shows numerical results for a jet impinging onto a flat plane covered with a layer of a porous material. Porosity of the porous layer is varied in order to analyze its effect on the local distribution of Nu. Macroscopic equations for mass and momentum ae obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling near the stagnation region.

Laminar Natural Convection Inside a Wavy Enclosure Heated From Top and Uniformly Cooled From the Bottom and Both Sides

2005 ◽  
Author(s):  
Amaresh Dalal ◽  
Manab Kumar Das
Keyword(s):  
Natural Convection ◽  
Simple Algorithm ◽  
Governing Equations ◽  
Square Cavity ◽  
Integral Forms ◽  
Nusselt Number Distribution ◽  
Laminar Natural Convection ◽  
Lower Temperature ◽  
Volume Method ◽  
Spatially Varying

In the present paper, natural convection inside a square cavity with one and three undulations on the top wall has been carried out. The top wall is heated by a spatially varying temperature and other three walls are kept constant lower temperature. The integral forms of the governing equations are solved numerically using finite-volume method in non-orthogonal body-fitted coordinate system. SIMPLE algorithm with higher-order up-winding scheme are used. The streamlines and isothermal lines are presented for different Rayleigh number (103-106) and a fluid having Prandtl number 0.71. Results are presented in the form of local and average Nusselt number distribution for two different undulations (1 and 3) with wave amplitude of 0.05.

THE INVESTIGATION OF THERMOHYDRODYNAMIC CHARACTERISTIC OF SINGLE AXIAL GROOVE JOURNAL BEARINGS WITH FINITE LENGTH BY USING CFD TECHNIQUES

2013 ◽  
Vol 10 (05) ◽  
pp. 1350031 ◽  
Author(s):  
ALIREZA ARAB SOLGHAR ◽  
S. A. GANDJALIKHAN NASSAB
Keyword(s):  
Stokes Equations ◽  
Control Volume ◽  
Three Dimensional ◽  
Theoretical Data ◽  
Simple Algorithm ◽  
Journal Bearings ◽  
Rate Equations ◽  
Navier Stokes ◽  
Computational Domain ◽  
Oil Flow

The three-dimensional steady state thermohydrodynamic (THD) analysis of an axial grooved oil journal bearing is obtained theoretically. Navier–Stokes equations are solved simultaneously along with turbulent kinetic energy and its dissipation rate equations coupled with the energy equation in the lubricant flow and the heat conduction equation in the bush. The AKN low-Re κ–ε turbulence model is used to simulate the mean turbulent flow field. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid and the governing equations are transformed into the computational domain. Discretized forms of the transformed equations are obtained by the control volume method and solved by the SIMPLE algorithm. The numerical results of this analysis can be used to investigate the pressure distribution, volumetric oil flow rate and the loci of shaft in the journal bearings. To validate the computational results, comparison with the experimental and theoretical data of other investigators is made, and reasonable agreement is found.

Influence of Rotor-Stator Interaction on Flow Stability in Centrifugal Pump Based on Energy Gradient Method

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Lu-Lu Zheng ◽  
Hua-Shu Dou ◽  
Wei Jiang ◽  
Xiaoping Chen ◽  
Zuchao Zhu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Energy Gradient ◽  
Rotor Stator Interaction ◽  
Volume Method

AbstractNumerical simulation is performed for the three-dimensional turbulent flow field in a centrifugal pump by solving the Reynolds-averaged Navier-Stokes equations and the RNG k-epsilon turbulent model. The finite volume method and the SIMPLE algorithm are employed for the solution of the system. All the parameters in the centrifugal pump at different blade angular positions are obtained by simulation. The flow structure is analyzed and the distributions of the energy gradient function

Flow Investigations in an Aero Gas Turbine Engine Afterburner

2005 ◽  
Author(s):  
S. Suresh Kumar ◽  
V. Ganesan
Keyword(s):  
Gas Turbine ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Reacting Flow ◽  
Isothermal Model ◽  
Turbine Engine ◽  
Turbulence Effects ◽  
Dissipation Model ◽  
Volume Method

This paper is concerned with the prediction of flow and flame characteristics behind complex flame stabilizer used in aero gas turbine afterburners. The numerical calculation is performed using SIMPLE algorithm with unstructured grid arrangement in which time averaged transport equation for mass, momentum, turbulence and energy are solved using finite volume method. The turbulence effects are simulated using RNG κ-ε model. Flow analysis has been carried out for the non-reacting and reacting conditions. Meshing of the flow domain is done in GAMBIT. A detailed analysis of non-reacting flow in a 60°sector afterburner from inlet to exit of the afterburner is carried out in FLUENT solver code. The various thermodynamic properties are analyzed and presented along the length of the afterburner. Three different combustion models viz. prePDF, eddy dissipation and finite rate/eddy dissipation model are used in order to predict the reacting flow. An experimental investigation of the three-dimensional confined flow fields behind a “V” shaped complex flame stabilizer in an isothermal model of an afterburner is carried out to validate the CFD code. From the present study it is concluded that the prediction procedure adopted especially for non-reacting flow can be used with confidence in the development of an afterburner at a lower cost. Since measurements were not possible under reacting conditions no attempt has been made for reacting flow validation.

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