THERMAL COMFORT IN FOOTWEAR, AN ASSESSMENT WITH OPENFOAM

Data from 2012 reported that the footwear industry accounted for ca 0.5% of the total EU manufacturing, employing 280 000 people. However, most of the production is mainly comprised in three countries: Italy, Spain and Portugal [1]. For the latter, data from 2018, reported that this industry was becoming one the most important sectors of the Portuguese economy, exporting ca. 95 % of the total production, resulting in a revenue of more than 1900 million euros and employing more than 40 000 people [2]. However, this sector is mainly comprised of small to medium sized companies, most of which cannot afford much R&D so the main method for innovation is through trial and error. To face this problem, a cluster of companies from the Portuguese footwear industry and several research centers and Universities joined in a cooperation project called FAMEST, acronym for Footwear, Advanced Materials, Equipment’s and Software Technologies. Through it, Portuguese companies are expected to improve their competitiveness in international markets by increasing the added value of their products. Within FAMEST, one subproject aims at the development of open source tools for supporting the industry through Computer Assisted Engineering (CAE) tools. OpenFOAM® is nowadays a staple for open source computational modelling and is extensively used in both academia and industry. In this work, we illustrate the application of a calculation procedure implemented for assessing thermal comfort in footwear. For that purpose, we specifically evaluated the heat transfer between a feet system, comprising the foot and footwear (with several components), and the environment, in order to identify the system temperature distribution and, consequently, the comfort perceived by the user. The foot was modeled as having a heat source term for human heat generation and different thermal material properties were assign to the components of the footwear. The CAE tool is based on chtmultiregionsimpleFoam solver, that allows to model the heat exchange in solid/fluid systems comprising different materials.

ACKNOWLEDGEMENT This work was funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020/UIDP/05256/2020 and FAMEST - Footwear, Advanced Materials, Equipment’s and Software Technologies (POCI-01-0247-FEDER-024529). The authors also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER-000086) and Minho Advanced Computing Center (MACC).

REFERENCES [1]- The EU footwear industry, https://ec.europa.eu/growth/sectors/fashion/footwear/eu-industry_en, accessed on the 04/03/2020 [2] – Facts and number Portuguese Shoe Industry, https://www.apiccaps.pt/getfilev2/?f=/2018-facts--numbers.pdf&idf=MzEzMg== , accessed on the 04/03/2020