scholarly journals Study of fluid flow inside closed cavities using computational numerical methods

2021 ◽  
Vol 12 ◽  
pp. 4
Author(s):  
Mariya Helen Mercy JK ◽  
Prabhakar V
Keyword(s):  
Fluid Flow ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Vertical Wall ◽  
Bottom Wall ◽  
Left Wall ◽  
Thermal Boundary Conditions ◽  
Left And Right ◽  
Triangular Enclosure ◽  
Penalty Finite Element Method

The temperature distribution and distortion of fluid flow inside the closed cavities, square and triangle, are studied for different boundary conditions. Two different conditions of thermal boundary conditions are used for studying square cavities: (i) Left wall is hot, right wall is cold, top and bottom walls are adiabatic. (ii) Left and right walls are cold, top wall is adiabatic, bottom wall is hot. For triangular enclosure, the boundary conditions are (i) the vertical wall is insulated, bottom wall is hot. (ii) The vertical wall is hot, the bottom wall insulated and the inclined walls are kept cold in both conditions. The velocity of the flow is observed by means of stream function and the temperature distribution is displayed in the form of contours. The study is carried out in ANSYS software. The mathematical procedure for solving the nonlinear system of partial differential equations by penalty finite element method involving bi-quadratic elements is also discussed in detail.

Effects of Thermal Boundary Conditions on Entropy Generation During Natural Convection in a Differentially Heated Square Cavity

2010 ◽  
Author(s):  
Ram Satish Kaluri ◽  
Tanmay Basak ◽  
A. R. Balakrishnan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Entropy Generation ◽  
Bottom Wall ◽  
Convection Flow ◽  
Uniform Heating ◽  
Square Cavity ◽  
Fluid Friction ◽  
Thermal Boundary Conditions

Natural convection is a widely occurring phenomena which has important applications in material processing, energy storage devices, electronic cooling, building ventilation etc. The concept of ‘entropy generation minimization’, which is a thermodynamic approach for optimization, may be very useful in designing efficient thermal systems. In the current study, entropy generation in steady laminar natural convection flow in a square cavity is studied with following isothermal boundary conditions: (1) Bottom wall is uniformly heated (2) Bottom wall is sinusoidally heated. The side walls are maintained cold and the top wall is maintained adiabatic. The thermal boundary condition in non-uniform heating case (case 2) is such that the dimensionless average temperature of the bottom wall is equal to that of uniform heating case (case 1). The prime objective of this work is to investigate the influence of uniform and non-uniform heating on entropy generation. The governing mass, momentum and energy equations are solved using Galerkin finite element method. Streamlines, isotherms, contour maps of entropy generation due to heat transfer and fluid friction are studied for Pr = 0.01 (molten metals) and 7 (water) in range of Ra = 103–105. Detailed analysis on the effect of uniform and non-uniform thermal boundary conditions on entropy generation due to heat transfer and fluid friction has been presented. Also, the average Bejan’s number which indicates the relative dominance of entropy generation due to heat transfer or fluid friction and the total entropy generation are studied for each case.

Assessment on the Thermal Stresses of Concrete Bridge Piers under Solar Radiation

2012 ◽  
Vol 204-208 ◽  
pp. 2045-2050 ◽  
Author(s):  
Pei Song Gong ◽  
Bo Chen ◽  
Chun Fang Song ◽  
Xiu Li Li
Keyword(s):  
Temperature Distribution ◽  
Boundary Conditions ◽  
Thermal Stresses ◽  
Numerical Models ◽  
Bridge Pier ◽  
Concrete Bridge ◽  
Time Varying ◽  
Thermal Boundary Conditions ◽  
Infrared Imager ◽  
Structural Temperature

The time-varying thermal stresses of a concrete pier are actively studied in this study with the aiding of the commercial package ANSYS. Thermal boundary conditions are utilized to obtain the temperature distribution of the concrete bridge pier. The surface temperature of the pier is measured by using a thermal infrared imager at different time instants. The different boundary conditions are applied to determine the structural temperature distribution and compute the thermal deformation. The made observations demonstrate that the horizontal deformation is much larger than that in vertical deformation due to the influence of the constraints on the top and bottom sides of the pier. The thermal stresses of the example bridge pier are not very large except for the local areas on top of the piers. It is seen that the numerical models can successfully predict the structural time-varying temperature effects

Asymmetric Conduction in an Infinite Functionally Graded Cylinder: Two-Dimensional Exact Analytical Solution Under General Boundary Conditions

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Amin Amiri Delouei ◽  
Amin Emamian ◽  
Sajjad Karimnejad ◽  
Hasan Sajjadi ◽  
Dengwei Jing
Keyword(s):  
Temperature Distribution ◽  
Boundary Conditions ◽  
Thermal Stresses ◽  
Exact Analytical Solution ◽  
Full Range ◽  
Functionally Graded ◽  
Graded Materials ◽  
Thermal Boundary Conditions ◽  
Essential Parameter ◽  
General Linear Boundary Conditions

Abstract This paper focuses on using an analytical method to obtain an exact solution for a long cylindrical vessel made of functionally graded materials (FGMs). Heat conduction equations are assumed to be in both radial and circumferential directions. The conduction coefficients are considered as different power-law functions of the radius. The general linear boundary conditions are adopted to make the solution applicable to the full range of problems. The obtained solution is successfully validated. Through solving illustrative test examples, the effects of material constants and boundary conditions on temperature distribution are studied. The obtained formulation can be utilized for tailoring of FGM based on the actual sophisticated thermal boundary conditions in the production process. The current analytical findings can help to manage the temperature distribution in FGMs which is an essential parameter in controlling the thermal stresses.

Optimal Design of Heat Transfer and Fluid Flow Using Adjoint Sensitivity Analysis

2007 ◽  
Author(s):  
Kazunari Momose ◽  
Kaoru Ikejima ◽  
Hideshi Ishida ◽  
Genta Kawahara
Keyword(s):  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Fluid Flow ◽  
Boundary Conditions ◽  
Descent Method ◽  
Steepest Descent Method ◽  
Design Parameters ◽  
Adjoint Sensitivity Analysis ◽  
Adjoint Sensitivity ◽  
Thermal Boundary Conditions

An optimization system based on adjoint sensitivity analysis has been developed for heat transfer and fluid flow design, the objective of which is, for example, the maximization of local temperature or to achieve the target temperature distributions in specific regions by controlling the flow and thermal boundary conditions as the design parameters. Using the system, the sensitivities on whole boundary can be obtained by a couple of numerical computations of the conventional forward problem and the corresponding adjoint problem. Moreover, by combining with a commercial CFD software as a front end and with the steepest descent method as an optimizer, we show that the flow and thermal boundary conditions can automatically be optimized.

scholarly journals Boundary Conditions for Simulations of Fluid Flow and Temperature Field during Ammonothermal Crystal Growth—A Machine-Learning Assisted Study of Autoclave Wall Temperature Distribution

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 254 ◽  
Author(s):  
Saskia Schimmel ◽  
Daisuke Tomida ◽  
Makoto Saito ◽  
Quanxi Bao ◽  
Toru Ishiguro ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Machine Learning ◽  
Boundary Condition ◽  
Fluid Flow ◽  
Crystal Growth ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Wall Temperature ◽  
Domain Size ◽  
Transfer Model

Thermal boundary conditions for numerical simulations of ammonothermal GaN crystal growth are investigated. A global heat transfer model that includes the furnace and its surroundings is presented, in which fluid flow and thermal field are treated as conjugate in order to fully account for convective heat transfer. The effects of laminar and turbulent flow are analyzed, as well as those of typically simultaneously present solids inside the autoclave (nutrient, baffle, and multiple seeds). This model uses heater powers as a boundary condition. Machine learning is applied to efficiently determine the power boundary conditions needed to obtain set temperatures at specified locations. Typical thermal losses are analyzed regarding their effects on the temperature distribution inside the autoclave and within the autoclave walls. This is of relevance because autoclave wall temperatures are a convenient choice for setting boundary conditions for simulations of reduced domain size. Based on the determined outer wall temperature distribution, a simplified model containing only the autoclave is also presented. The results are compared to those observed using heater-long fixed temperatures as boundary condition. Significant deviations are found especially in the upper zone of the autoclave due to the important role of heat losses through the autoclave head.

The influence of thermal radiation on unsteady free convection in inclined enclosures filled by a nanofluid with sinusoidal boundary conditions

2018 ◽  
Vol 28 (8) ◽  
pp. 1738-1753 ◽  
Author(s):  
Mikhail A. Sheremet ◽  
Ioan Pop ◽  
Alin V. Rosca
Keyword(s):  
Natural Convection ◽  
Temperature Distribution ◽  
Thermal Radiation ◽  
Convective Flow ◽  
Vertical Wall ◽  
Radiation Parameter ◽  
Square Cavity ◽  
Left Wall ◽  
Content Type ◽  
Sinusoidal Temperature

Purpose The purpose of this study is a numerical analysis of transient natural convection in an inclined square cavity filled with an alumina-water nanofluid under the effects of sinusoidal wall temperature and thermal radiation by using a single-phase nanofluid model with empirical correlations for effective viscosity and thermal conductivity. Design/methodology/approach The domain of interest includes the nanofluid-filled cavity with a sinusoidal temperature distribution along the left vertical wall. Horizontal walls are supposed to be adiabatic, while right vertical wall is kept at constant low temperature. Temperature of left wall varies sinusoidally along y-coordinate. It is assumed in the analysis that the thermophysical properties of the fluid are independent of temperature and the flow is laminar. The governing equations have been discretized using the finite difference method with the uniform grid. Simulations have been carried out for different values of the Rayleigh number, cavity inclination angle, nanoparticles volume fraction and radiation parameter. Findings It has been found that a growth of radiation parameter leads to the heat transfer enhancement and convective flow intensification. At the same time, an inclusion of nanoparticles illustrates a reduction in the average Nusselt number and fluid flow rate. Originality/value The originality of this work is to analyze unsteady natural convection in a square cavity filled with a water-based nanofluid in the presence of a sinusoidal temperature distribution along one wall. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors, electronics, etc.

Natural convection combined with thermal radiation in a square cavity filled with a viscoelastic fluid

2018 ◽  
Vol 28 (3) ◽  
pp. 624-640 ◽  
Author(s):  
Mikhail A. Sheremet ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermal Radiation ◽  
Viscoelastic Fluid ◽  
Vertical Wall ◽  
Temperature Fields ◽  
Radiation Parameter ◽  
Square Cavity ◽  
Left Wall ◽  
Content Type

Purpose The purpose of this paper is to study natural convective heat transfer and viscoelastic fluid flow in a differentially heated square cavity under the effect of thermal radiation. Design/methodology/approach The cavity filled with a viscoelastic fluid is heated uniformly from the left wall and cooled from the right side while insulated from horizontal walls. Governing partial differential equations formulated in non-dimensional stream function, vorticity and temperature with corresponding boundary conditions have been solved by finite difference method of second order accuracy. The effects of Rayleigh number (Ra = 1e+3−1e+5), radiation parameter (Rd = 0 − 10), Prandtl number (Pr = 1 − 30) and elastic number (E = 0.0001 − 0.001) on flow patterns, temperature fields, average Nusselt number at hot vertical wall and rate of fluid flow have been studied. Findings It has been found that a growth of elastic number leads to the heat transfer reduction and convective flow attenuation. The heat conduction is a dominating heat transfer mechanism for high values of radiation parameter. Originality/value The originality of this work is to analyze heat transfer and fluid flow of a viscoelastic fluid inside a differentially heated cavity. The results would benefit scientists and engineers to become familiar with the flow and heat behavior of non-Newtonian fluids, and the way to predict the properties of this flow for possibility of using viscoelastic fluids in compact heat exchangers, electronic cooling systems, polymer engineering, etc.

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