Transp Porous Med (2011) 89:165–183 DOI 10.1007/s11242-011-9763-4 Nanofins as a Means of Enhancing Heat Transfer: Leading Order Results Peter Vadasz Received: 29 September 2010 / Accepted: 5 April 2011 / Published online: 21 April 2011 © Springer Science+Business Media B.V. 2011 Abstract The porous media approach is being adapted to a system of nanoparticles that are attached to a solid surface (a metal wire) embedded into a stagnant fluid, forming by design nanofins around the wire. The analyzed system resembles the Transient Hot Wire experimental method used in evaluating the thermal conductivity of a fluid or nanofluid sus- pensions. Since the attachment of the nanoparticles to the wire is done by design (as distinct from uncontrolled agglomeration around the wire), one major objective in such a design is attempting to enhance the heat transfer from the wire. The latter objective is analyzed via a short times approximation of the solution. Preliminary results based on the leading order solution shows that such a heat transfer enhancement is indeed possible and presents major advantages compared to commonly used macro-fins. Keywords Nanofins · Transient hot wire · Porous media · Nanofluids · Effective thermal conductivity List of Symbols Variables A Cross sectional area of the wire (m 2 ) A sf Solid–fluid interface heat transfer area (m 2 ) c p Fluid’s specific heat for the single phase (J/kg K) (dimensional) c p,f , c s Fluid and solid phases specific heat, respectively (J/kg K) (dimensional) E i Exponential integral function P. Vadasz (B ) Department of Mechanical Engineering, Northern Arizona University, P. O. Box 15600, Flagstaff, AZ 86001, USA e-mail: peter.vadasz@nau.edu P. Vadasz Faculty of Engineering, University of KZ Natal, Durban 4041, South Africa 123