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The present work proposes a simple lattice Boltzmann model for incompressible axisymmetric thermal flows through porous media. By incorporating forces and source terms into the lattice Boltzmann equation, the incompressible Navier-Stokes equations are recovered through the Chapman-Enskog expansion. It is found that the added terms are just the extra terms in the governing equations for the axisymmetric thermal flows through porous media compared with the Navier-Stokes equations. Four numerical simulations are performed to validate this model. Good agreement is obtained between the present work and the analytic solutions and/or the results of previous studies. This proves its efficacy and simplicity regarding other methods. Also, this approach provides guidance for problems with more physical phenomena and complicated force forms.

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Summary The effect of wick structure on the performance of capillary‐driven heat pipes is analyzed numerically. Three types of wick structure are investigated: copper screen, sintered steel, and sintered copper. Using lattice Boltzmann method, the entire heat pipe is modeled including heat transfer through the wall and heat and mass transfer in the liquid‐wick and vapor regions. Comparison between the present model and analytical results available in the literature shows excellent agreement. The liquid velocity profiles and temperature distribution in the wall are also presented for different working fluids and discussed. Comparison is made between performance of heat pipes with different wick structures and working fluids. Results indicate better performance, with a factor up to 1.7, of heat pipes using water as working fluid with sintered copper structure than with other wick structures. In addition, it is found that the larger the liquid's radial velocity, the less the thermal resistance at given heat input power. Both a simple equivalent resistance circuit and numerical data suggest strongly that the most impactive fluid properties on the heat pipe performance seem to be the latent heat of vaporization, the molecular mass, the change rate of the saturation pressure with respect to temperature, and the conductivity of its liquid phase.