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TECHNICAL BRIEFS

# A Coupled Map Lattice Model of Flow Boiling in a Horizontal Tube

[+] Author and Article Information
P. S. Ghoshdastidar1

Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, U.P. 208016, Indiapsg@iitk.ac.in

Indrajit Chakraborty

Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, U.P. 208016, Indiaindrac@iitk.ac.in

1

To whom all correspondence should be addressed.

J. Heat Transfer 129(12), 1737-1741 (Mar 27, 2007) (5 pages) doi:10.1115/1.2768102 History: Received February 05, 2006; Revised March 27, 2007

## Abstract

In this work laminar, stratified flow boiling of water is simulated qualitatively by the coupled map lattice (CML) method. The liquid is entering a constant wall temperature horizontal tube ($Tw>Tsat$ at $pentrance$) in a subcooled condition. A CML is a dynamical system with discrete-time, discrete-space, and continuous states. The procedure basically consists of the following steps: (i) Choose a set of macroscopic variables on a lattice; (ii) decompose the problem into independent components, such as convection, diffusion, phase change, and so on; (iii) replace each component by a simple parallel dynamics on a lattice; and (iv) carry out each unit dynamics successively in each time step until some termination criterion is satisfied. In the present problem, the termination criterion is the laminar-turbulent transition, and hence, the results do not correspond to the steady state. The present modeling by CML is based on the assumption that the flow boiling is governed by (i) nucleation from cavities on the heated surface and migration of vapor into the core, (ii) forced convection, and (iii) phase change in the fluid bulk and mixing. The stirring action of the bubbles is modeled by increasing the fluid momentum and thermal diffusivities by an enhancement factor. The results show that the CML has been able to model flow boiling in a realistic manner.

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## Figures

Figure 1

Flow geometry and the computational domain

Figure 2

Computational domain and lattices in (r,θ) planes

Figure 3

Heat flux versus axial coordinate plot for water

Figure 4

Comparison of hmean versus z plots for different wall temperatures

Figure 5

Comparison of f versus z plots for different ΔTsub

Figure 6

Comparison of hmean versus z plots for different axial pressure gradients

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