Download or read book Simulation of Natural Convection Heat Transfer in an Enclosed Cavity Using Constrained Interpolated Profile Navier stokes Equation cipnse Method written by Chee Kin Loh and published by . This book was released on 2010 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Parallel Computations of Natural Convection Flow in a Tall Cavity Using an Explicit Finite Element Method written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Galerkin Finite Element Method was used to predict a natural convection flow in an enclosed cavity. The problem considered was a differentially heated, tall (8:1), rectangular cavity with a Rayleigh number of 3.4 x 105 and Prandtl number of 0.71. The incompressible Navier-Stokes equations were solved using a Boussinesq approximation for the buoyancy force. The algorithm was developed for efficient use on massively parallel computer systems. Emphasis was on time-accurate simulations. It was found that the average temperature and velocity values can be captured with a relatively coarse grid, while the oscillation amplitude and period appear to be grid sensitive and require a refined computation.

Download or read book Numerical Solutions for a Comparison Problem on Natural Convection in an Enclosed Cavity written by I. P. Jones and published by . This book was released on 1981 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Simulations of Thermally Induced Convection in an Enclosed Cavity written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The simulations reported establish benchmark comparisons of different techniques of solving the Navier-Stokes and thermal energy equations for a particular thermally driven flow. Included also is a brief analysis of the results and some comparisons with previous solutions. The second section of this paper contains a result at a higher Rayleigh number and some tilted cavity results, which were performed, in part, as potential candidates for more difficult follow-up benchmark problems.

Download or read book NATURAL CONVECTION INSIDE A CIRCULAR CAVITY written by POA T. CHU and published by . This book was released on 1961 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Solutions for a Comparison Problem on Natural Convection in an Enclosed Cavity written by I. P. Jones and published by . This book was released on 1981 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Natural Convection in Cavities Using the Finite Analytic Method written by Mehrdad Rahdar and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Optical Study of Natural Convection in an Enclosed Cavity written by N. A. Grosek and published by . This book was released on 1982 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of natural convective heat transfer in a two-dimensional enclosed cavity was conducted with various cavity geometries. The square cavity was divided by a vertical or diagonal partition. Convective heat transfer rates were determined from interferograms. Heat transfer was reduced by partitioning, but by less than 50%. Effects of left and right diagonal partitions were temperature dependent. This was attributed to the presence of complex radiation effects. (Author).

Download or read book Numerical Simulation of Natural Convection in Closed Containers Using a Fully Implicit Method written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical solutions have been obtained for two-dimensional free convective flow in rectangular and annular cavities using the strongly implicit procedure (SIP) and the cyclic reduction-fast Fourier transform (CR-FFT) technique. Rayleigh numbers range from 104 to 106, Prandtl numbers from 0.713 to 103, radius ratios from 1 to 3 (annular cavities), and aspect ratios (height/width) from 1 to 15. Motion is generated by either uniformly heating the bottom wall or heating a vertical wall (nondimensional temperature of 1) and cooling the opposite wall (nondimensional temperature of 0). Both time-dependent and steady state solutions confirm results previously obtained by others. The computational speed of the SIP and CR-FFT methods is very fast. Because SIP uses a common set of matrix algorithms, the governing equations of motion can be solved simultaneously without major modification to the method for each equation.

Download or read book Numerical Simulation of Natural Convection in a Radiating Fluid Enclosed in a Cavity written by G. Lauriat and published by . This book was released on 1982 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Natural Convection in Cavities Using the Finite Analytic Method microform written by Mehrdad Rahdar and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1998 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Natural Convection from a Horizontal Heat Sink Numerical Simulation Using Fluent 19 2 written by Hesham Khalil and published by Fluent Tutorials. This book was released on 2019-03-02 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural convection is a phenomenon occurs when heat is transferred to a fluid, which raises its temperature and decreases its density and consequently makes it flows upward. This book is a complete tutorial on how to simulate this kind of phenomenon using ANSYS Fluent 19.2. This is applied to a simple application of cooling a small surface using a heat sink. The tutorial starts with creating the 3D domain itself inside ANSYS DesignModeler, then discretizing it (Meshing) in ANSYS Meshing application. After that, the model is defined in Fluent with the appropriate boundary conditions. Finally, the output data is processed in Fluent to see the resulting flow around the heat sink and the temperature distribution in both the fluid and the heat sink itself.This a tutorial for the complete steps required to complete this kind of simulation. It is presented in the form of high-resolution screenshots of the applications' windows which are preceded by a textual description of the steps. Also, some of these screenshots are followed by an explanation of the different choices when seen appropriate.

Download or read book Computational Fluid Dynamics CFD Modeling of Mixed Convection Flows in Building Enclosures written by Alexander Kayne and published by . This book was released on 2012 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2-D closed vertical cavity, second for forced convection in a 2-D rectangular cavity and the third for mixed convection in a 2-D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-[epsilon] two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.

Download or read book Computational Fluid Dynamic Modeling of Natural Convection in Vertically Heated Rods written by Mahesh Surendran and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural convection is a phenomenon that occurs in a wide range of applications such as cooling towers, air conditioners, and power plants. Natural convection may be used in decay heat removal systems such as spent fuel casks, where the higher reliability inherent of natural convection is more desirable than forced convection. Passive systems, such as natural convection, may provide better safety, and hence have received much attention recently. Cooling of spent fuel rods is conventionally done using water as the coolant. However, it involves contaminating the water with radiation from the fuel rods. Contamination becomes dangerous and difficult for humans to handle. Further, the recent nuclear tragedy in Fukushima, Japan has taught us the dangers of contamination of water with nuclear radiation. Natural convection can perhaps significantly reduce the risk since it is self-sufficient and does not rely on other secondary system such as a blower as in cases of forced convection. The Utah State University Experimental Fluid Dynamics lab has recently designed an experiment that models natural convection using heated rod bundles enclosed in a rectangular cavity. The data available from this experiment provides and opportunity to study and validate computational fluid dynamics(CFD)models. The validated CFD models can be used to study multiple configurations, boundary conditions, and changes in physics(natural and/or forced convection). The results are to be validated using experimental data such as the velocity field from particle image velocimetry (PIV), pressure drops across various sections of the geometry, and temperature distributions along the vertically heated rods. This research work involves modeling natural convection using two-layer turbulence models such as k - Îæ and RST (Reynolds stress transport) using both shear driven (Wolfstein) and buoyancy driven (Xu) near-wall formulations. The interpolation scheme employed is second-order upwinding using the general purpose code STAR-CCM+. The pressure velocity coupling is done using the SIMPLE method. It is ascertained that turbulence models with two-layer formulations are well suited for modeling natural convection. Further it is established that k - Îæ and Reynolds stress turbulence models with the buoyancy driven (Xu)formulation are able to accurately predict the flow rate and temperature distribution.

Download or read book Natural Convection in a Square Cavity written by Graham De Vahl Davis and published by . This book was released on 1982 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of Natural Convection Instabilities in Closed Cavities with Non isothermal Walls written by Sneha Rajeev Sondur and published by . This book was released on 2020 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural convection inside closed cavities has been investigated extensively over the years owing to its application in several industrial processes. Amongst these, the most commonly studied configuration is that of natural convection in air-filled cavities with isothermal vertical walls maintained at different temperatures, which promote a unicellular base air-flow pattern. In the present work, natural convection of air in annular and rectangular cavities with non-isothermal walls supporting a bi-cellular base air-flow pattern is explored both experimentally and numerically. The experiments and numerical studies described in this work represent a significant departure from the more familiar problem of stability of unicellular convection in closed cavities and are therefore a novel addition to the body of literature available for natural convection systems. Two experimental systems, one annular and one rectangular were constructed to study the stability of natural convection in tall, closed air-filled cavities with non-isothermal walls. The thermal boundary conditions applied on the cavities' vertical walls were such that the temperature of one vertical wall was higher than that of the opposing wall in the top portion of the cavity and lower than it in the bottom portion of the cavity. The Rayleigh number or buoyant potential of the bi-cellular (base) air-flow was successively increased/decreased over the course of several experiments, and the stability of flow inside these cavities was studied via monitoring of air temperatures. At low Rayleigh numbers, a steady flow regime was observed for both annular and rectangular cavities. With an increase in Rayleigh number transitions to 3D asymmetric periodic flows, quasi-periodic flows, intermittent flows, and chaotic flows were observed for the annular cavity. On the other hand, transitions from steady to 2D periodic flow, then to 3D periodic flow and finally to chaotic flow were observed for the rectangular cavity. The observed flow bifurcations, the resultant oscillation frequencies, phases, and amplitudes mapped relative to the wall thermal boundary conditions for both annular and rectangular experimental systems are presented in this work. 2D and 3D CFD models of the two experimental systems were developed using the commercial CFD code Simcenter StarCCM+ in order to numerically predict the experimentally observed unsteady natural convection flows. The experimentally imposed thermal boundary conditions were used as inputs for the CFD models. The accuracy of these CFD models in predicting experimental flows is discussed, and comparisons are made between the prediction capabilities of the 2D and 3D CFD models. Furthermore, the numerical simulations and frequency analysis of the experimental data are able to shed light on the primary instability modes causing the transitions from steady to unsteady flows. These instability mechanisms responsible for bifurcations observed in the annular and rectangular cavity are discussed in detail. This work also includes a benchmarking exercise for the commercial CFD code Simcenter StarCCM+ for problems of natural convection in cavities under both Boussinesq and non-Boussinesq temperature conditions. In addition, numerical simulations to understand the impact of non-Boussinesq temperature conditions and variable thermophysical fluid properties on the natural convection instabilities observed in closed, tall, air-filled rectangular and annular cavities with isothermal walls are performed.

Download or read book Numerical Investigation of Natural Convection and Entropy Generation of Water Near Density Inversion in a Cavity Having Circular and Elliptical Body written by Nguyen Minh Phu and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this chapter, a water-filled square cavity with left hot wall and right cold wall was numerically investigated. The hot and cold wall temperatures are 10¬∞C and 0¬∞C respectively to examine the density inversion of natural convection water, i.e. water at 4¬∞C. In the middle of the square, there are circular and elliptical bodies to study fluid,Äìstructure interaction in terms of the thermohydraulic behavior and entropy generation. 2D numerical simulation was performed using finite volume method in Ansys fluent software with the assumption of laminar flow. The simulation results are compared with benchmark data to determine reliability. The results indicate that the body insertions increase the convection heat transfer coefficients at the best heat transfer positions due to impingement heat transfer. An increase in heat transfer rate of 1.06 times is observed in the case of circular body compared to none. There are three primary eddies in the cavity with bodies, whereas the cavity without body has two primary eddies. Maximum entropy generation was found in the upper right corner of cavity mainly due to high horizontal temperature gradient. Bodies of circle and vertical ellipse have almost the same thermohydraulic and entropy generation characteristics due to the same horizontal dimension which mainly effects on the downward natural convection current. The entropy generation of cavity with circular body is 1.23 times higher than that of the cavity without body. At positions y/L¬†=¬†1 on the hot wall and y/L¬†=¬†0.74 on the cold wall, the convection heat transfer coefficient is close to zero due to stagnant fluid.