Effect of the magnetic field orientation on the damping of liquid metal free surface waves in the processing of materials Gerardo Alcal  a a , Michel Rivero b , Sergio Cuevas a, * a Instituto de Energías Renovables, Universidad Nacional Aut onoma de M exico, Temixco, Morelos 62580, Mexico b Instituto Tecnol ogico de la Laguna, Divisi on de Posgrado e Investigaci on, Torre on, Coahuila 27000, Mexico article info Article history: Received 31 January 2014 Received in revised form 23 August 2014 Accepted 6 September 2014 Available online 16 September 2014 Keywords: Magnetic damping Electromagnetic processing of materials Liquid metal Free surface abstract The actual requirements of high-grade materials lead to a constant increase in energy consumption, creating the necessity of new efficient and environmentally friendly technologies. In the past decades, the Electromagnetic Processing of Materials (EPM) has been established as an alternative for the manipulation, monitoring and control of conducting materials such as liquid metals, semiconductors, molten salts, and electrolytes, during the processing stages. Besides the application of nonintrusive methods that allow a convenient handling of the material while keeping it free from contamination of external agents, EPM offers the possibility of a the rational use of energy and the search for environ- mentally friendly innovation technologies. This paper presents a specific application for the control of liquid metal free surface flows, namely, the damping of surface waves with a uniform magnetic field. The attention is mainly focused on the orientation of the applied magnetic field relative to the free surface, the effects of the depth of the fluid layer, and the surface tension. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Very intensive efforts are being carried out worldwide to pro- mote the development and use of energy sources not based in fossil fuels. It is hoped that alternative practices for energy production based in renewable sources will help to mitigate the severe envi- ronmental damages caused by an irrational use of carbon based fuels as well as to transit towards a sustainable society. But the goal of reaching sustainability is strongly linked not only to energy production but also to our patterns of energy consumption, particularly, to the way in which energy is used to produce the increasingly demanded high-tech products. For instance, metal- lurgical and computing industries base largely their development on the capability of elaborating new materials and creating pro- cedures for handling substances that require high purity levels. In general, the processing and production of advanced materials is nowadays one of the most energy consuming sectors and therefore, any improvement or innovation that leads to energy savings while keeping high quality standards in the production process results in substantial benefits from the financial and environmental points of view. Incidentally, it has been estimated that in 2003 the produc- tion of aluminum in the USA consumed 1.2% of the total electrical energy produced in that country [1]. The actual requirements of high-grade materials lead to an increase in energy consumption and the necessity of new efficient technologies. Most of these technologies use electricity as the main source of energy to achieve their purposes due to its high density, cleanliness and controllability. In the last decades, the Electromagnetic Processing of Materials (EPM) has emerged as a branch of science and engineering devoted to the application of electromagnetic interactions for the process- ing of materials [2,3]. Currently, there are many industrial appli- cations of EPM that use electromagnetic fields to control processes involving conductive fluids, such as liquid metals, molten salts or semiconductor materials. Although electromagnetic fields have been used in the metallurgical industry for many years, mainly for melting and refining metals or alloys, in the majority of applications the fundamental understanding of the involved phenomena was absent. It was in the last two decades of the Twentieth Century that more rational approaches of the non-intrusive action of electro- magnetic fields were implemented to the handling, control, transport, and monitoring of electrically conducting liquids in diverse industrial processes. * Corresponding author. E-mail addresses: gealp@ier.unam.mx (G. Alcal a), michel.rivero@tu-ilmenau.de (M. Rivero), scg@ier.unam.mx, secugs@gmail.com (S. Cuevas). Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng http://dx.doi.org/10.1016/j.applthermaleng.2014.09.015 1359-4311/© 2014 Elsevier Ltd. All rights reserved. Applied Thermal Engineering 75 (2015) 1296e1301