a b s t r a c tModeling the filtration of incompressible fluids through porous media requires dealing with different types of partial differential equations in the fluid and porous subregions of the computational domain. Such equations must be coupled through physically significant continuity conditions at the interface separating the two subdomains. To avoid the difficulties of this heterogeneous approach, a widely used strategy is to consider the Navier-Stokes equations in the whole domain and to correct them introducing suitable terms that mimic the presence of the porous medium. In this paper we discuss these two different methodologies and we compare them numerically on a sample test case after proposing an iterative algorithm to solve a Navier-Stokes/Forchheimer problem. Finally, we apply these strategies to a problem of internal ventilation of motorbike helmets.

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Articles you may be interested inA complete model of keyhole and melt pool dynamics to analyze instabilities and collapse during laser welding J. Laser Appl. 26, 042001 (2014); 10.2351/1.4886835Analytical and numerical computations of heat transfer in pulsed thermography applied to porous CFRP AIP Conf.Abstract. This work deals with a methodology for the numerical simulation of the inner ventilation of a motorcycle helmet, based on a thermo-fluid-dynamic model capable of describing evaporation-related heat transfer phenomena. The final purpose is the enhancment of the comfort of the rider and ultimately his safety. The fluid-dynamic problem concerns the modelization of the filtration of a flow over a porous medium, while the (decoupled) thermodynamic model is associated with the heat and sweat removal by means of the airflow. The latter is based on a set of evolution equations for the three scalar unknowns temperature, absolute humidity and sweat. Simulations on a sample 2D problem show the applicability of the methodology, highlighting the implicitly-defined free boundary separating the wet and dry regions as well as the zones where sweat accumulates.

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