Analysis of the Internal Ventilation for a Motorcycle Helmet

Abstract

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.

Navier–Stokes/Forchheimer models for filtration through porous media

“…We refer to [6,16] on how to include this boundary condition in the weak formulation. On the remaining boundaries we impose a zero airflow condition.…”

“…The distance between the channels is 50 mm, while the extension of the porous layers in the transversal direction is 40 mm. For more details we refer to [16].) An unstructured tetrahedral mesh of about 32 000 elements has been generated using freeFEM++.…”

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

“…A pure evaporation process was considered in Cimolin (2008) and Canuto & Cimolin (2010) for a motorcycle helmet model, in which…”

“…Mathematical modelling for heat and moisture transfer in textile materials has been studied by many authors, which is often described as a multicomponent compressible (Fan et al 2004;Li et al 2005;Huang et al 2008;Henrique et al 2009) or incompressible (Wang & Catton 2001;Cimolin 2008;Canuto & Cimolin 2010) fluid flow through porous textile media. Some earlier works can be found in David & Nordon (1939), Ogniewicz & Tien (1981) and Farnworth (1986) with relatively simple models.…”

“…Moreover, the system can be written in the same form as the single-component model studied by Le et al (1995), Cheng & Wang (2008), Choudhary et al (2004) and Fan et al (2004) with an additional (air) permeability K , which, in other words, represents the air resistance to the vapour motion. As the global velocity in textile materials is usually small, the problem in some other applications was considered approximately as an incompressible fluid flow (Wang & Catton 2001;Cimolin 2008;Canuto & Cimolin 2010).…”