Selected papers presented during the Numerical Heat Transfer 2012 International Conference (NHT2012) held on 4-6 September 2012 in Wroclaw, Poland

International Journal of Numerical Methods for Heat & Fluid Flow

ISSN: 0961-5539

Article publication date: 29 April 2014

208

Citation

(2014), "Selected papers presented during the Numerical Heat Transfer 2012 International Conference (NHT2012) held on 4-6 September 2012 in Wroclaw, Poland", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 24 No. 4. https://doi.org/10.1108/HFF-02-2014-0034

Publisher

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Emerald Group Publishing Limited


Selected papers presented during the Numerical Heat Transfer 2012 International Conference (NHT2012) held on 4-6 September 2012 in Wroclaw, Poland

Article Type: Guest editorial From: International Journal of Numerical Methods for Heat & Fluid Flow, Volume 24, Issue 4

This special issue of the International Journal of Numerical Methods for Heat and Fluid Flow comprises selected papers presented during the Numerical Heat Transfer 2012 International Conference (NHT2012). The conference was organised as a Special Interest Conference of the European Community on Computational Methods in Applied Sciences (ECCOMAS) and was held on 4-6 September 2012 in Wroclaw, Poland.

Papers published in this special issue have been selected to demonstrate, on the one hand, an overview of the conference topics and, on the other hand, to document the most important advances in numerical heat transfer. The special issue consists of 12 papers.

The issue starts with a contribution from Y. Jaluria entitled “Numerical modelling of multiple length scales in thermal transport processes”. This work was presented by Professor Y. Jaluria as the plenary keynote lecture. The author is discussing in his paper fundamentals of the numerical modelling of the multiple length scales processes of heat transfer. Together with the overview of different possible approaches he is also presenting results of solved exemplary engineering problems.

The next two papers deal with numerical heat problems in minichannels. Shian Li, Gongnan Xie, Bengt Sunden and Weihong Zhang in their work entitled “Computational Fluid Dynamics for Thermal Performance of a Water-Cooled Minichannel Heat Sink with Different Chip Arrangements” are discussing effectiveness of water-cooled minichannel technology. They carry out CFD computations for three different chip arrangements and present temperature distributions on the bottom chip surfaces as well as the chip performance in terms of its total thermal resistance.

S. Hozejowska and M.E. Poniewski in their work entitled “Application of adjustment calculus to the Trefftz method for calculating temperature field of the boiling liquid flowing in a minichannel” discuss numerical calculations of the two-dimensional temperature field in the boiling refrigerant flow through an asymmetrically heated vertical minichannel with a rectangular cross-section. The Authors use the Trefftz method and their considerations are limited to determining the continuous phase, i.e. liquid for bubbly and bubbly-slug flow. The calculations were based on the assumption that the unknown temperature field of the liquid satisfies the energy equation with frictional heat taken into account. The measurement data utilize in the analysis have been smoothed to reduce their errors.

The next two papers discuss different aspects of oxy-combustion. D.B. Ingham, M. Pourkashanian, A. Pranzitelli, K. Stechly, J. Szuhanszki and G. Wecel in their work entitled “CFD modelling of air and oxy-coal combustion” carry out Computational Fluid Dynamic study of air and oxy-combustion of pulverized coal in a 0.5 MW combustion test facility. Three cases were investigated: one air-fired and two oxy-fired with dry recycled flue gas. The fuel mass flow rate was kept constant for all cases. Obtained numerical results were compared with experimental data of surface incident radiation on the test facility walls and the exit flue gas temperature.

The work entitled “Simulations of the PC boiler equipped with complex swirling burners” is co-authored by W. Adamczyk, R. Bialecki, P. Kozolub, A. Ryfa, G. Wecel and G. Serwatka. In this work the combustion phenomena were simulated in an industrial pulverized coal boiler equipped with a complex swirl burners and super heaters section. Numerical simulations were carried out using the commercial ANSYS Fluent CFD code with a set of user defined functions. Particularly, the discrete phase Lagrangian model for tracking particles and combustion phenomena were used in a dispersed phase, whereas the Eulerian approach was applied for the volatiles combustion process modelling in a gaseous phase. Authors investigate also the influence of numerical model simplifications on calculated fields variables was investigated. Additionally, the industrial boiler working parameters response to the combustion technology change from air- to oxy-fuel combustion was examined.

The next three contributions discuss numerical modelling of fluid flows also coupled with energy equation and some other transport equation. M. Jaszczur is considering “Large Eddy Simulation of a Fully Developed Non-isothermal Turbulent Channel Flow”. The filtered Navier-Stokes and energy equations were solved numerically with dynamic subgrid-scale (SGS) model, standard Smagorinsky model or without additional model for the turbulent SGS stress and heat flux required to close the governing equations. The objective of this analysis was to check influence of the sub-filter models on the flow and thermal field. The influence of the models were tested in a comparison to the direct numerical simulations (DNS). Fluid statistics for most of models show fair agreement with the DNS data. It has been found that, even though the models reproduce accurately results for the flow field the thermal field computed using LES do not necessary match the DNS results.

The next paper presents one of the first studies to model the entire flow field history of a non-conventional shock tube with a non-uniform cross section beginning from the bursting of the diaphragm while simultaneously resolving the fine features of the reflected shock-boundary layer interaction and the post-shock region near the end wall, at conditions useful for chemical kinetics experiments. The conjugate axi-symmetric model developed by M. Lamnaouer, A.J. Kassab, E. Divo, R. Garza-Urquiza, P. Nolan and E. Petersen in their work “A Conjugate Axisymmetric Model of a High-Pressure Shock-Tube Facility” is capable to simulate the shock and expansion wave propagations and reflections as a result of reflected shock/boundary layer interaction or bifurcation. The robustness of the numerical model and the accuracy of the simulations were also confirmed by experimental data.

J. Smolka, A. Fic, A.J. Nowak, L. Kosyrczyk and Z. Bulinski in their work entitled “3-D periodic CFD model of the heating system in a coke oven battery” yield 3-D model of heating channels being a crucial part of coke oven battery. This model is based on CFD analysis of coke oven gas firing and it takes into account the recirculation of flue gasses between upward and downward heating channels. Analyzed periodicity of the fluid flow and heat transfer processes results from fuel reversion as well as from periodicity of coking process which lasts certain time and then fresh coal is loaded to the coking chambers. Obtained results are partially validated by operating data.

Two successive papers deal with different computational aspects of numerical heat transfer. The paper entitled “Unconditionally stable numerical scheme for natural convection problems” comes from B. Gorecki and J. Szumbarski. The work is focused on the implementation and investigation of the numerical features of the unconditionally stable numerical scheme including both energy transport and buoyancy force due to density gradient in the fluid and thus allowing simulation of both natural and forced convection problems. Having in mind engineering applications of the method, spatial discretization of the governing equations has been done using h/p spectral element formulation. This is a high order method capable of handling complex domains and providing geometrical flexibility of finite elements. Authors demonstrate also numerical efficiency of the in-house flow solver analysing three test cases: Poisson equation for pressure, advection-diffusion equation for velocity and finally advection-diffusion equation for energy transport.

The contribution entitled “Front tracking approach to modelling binary alloy solidification – accuracy verification and the role of dendrite growth kinetics” is co-authored by M. Seredynski and J. Banaszek. The paper concerns some aspects of micro-macroscopic modelling of binary alloy solidification and its main purpose is to endorse the idea of using a special post-calculating front tracking procedure, along with the enthalpy-porosity single continuum model is used in order to identify zones of different dendritic micro-structures developing in the mushy zone during cooling and solidification of a binary alloy. Authors also compare their approach with the commonly used alternative approach, based on the concept of a critical value of the solid volume fraction.

The last two papers present application of inverse modelling in the heat transfer problems. G. Wecel, Z. Ostrowski and P. Kozolub in their work entitled “Absorption Line Black Body Distribution Function evaluated with Proper Orthogonal Decomposition for mixture of CO2 and H2O” propose to use the proper orthogonal decomposition (POD) to generate absorption line black body distribution function (ALBDF) for a mixture of two radiating gases: CO2 and H2O, which are the main combustion products. Since ALBDF for different gas parameters correlates very well, the POD method is well suited for reproducing ALBDF for arbitrary gas parameters. The obtained POD interpolation base can be used to reproduce ALBDF for any gas mixture parameters which are in range of original data. Different sizes of basis vectors have been tested in ALBDF reproduction procedures.

The work entitled “Inverse thermal analysis of the neonatal brain cooling process” comes from J. Laszczyk, A. Maczko, W. Walas and A.J. Nowak. In this work the attempt was made to simulate numerically using ANSYS/fluent package the heat transfer in the neonatal body during the brain cooling process. The main aim of the analysis was to find the proper parameters of the process using inverse thermal analysis. The results of the numerical computations were compared with the data obtained from neonatologists.

I am indebted to all authors for their contributions to this special issue, for their cooperation and support. I hope that this issue provides a window on the current interests in numerical heat transfer, while at the same time documenting recent advances in this fascinating research area. I would also like to thank Professor R.W. Lewis for giving me the opportunity to edit this special issue. I also very grateful to Mrs G. Power for highly professional handling of this special issue of the HFF.

Professor Andrzej J. Nowak
Institute of Thermal Technology, Silesian Technical University, Gliwice, Poland

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