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(I) Effect of Deformation on the Thermal Conductivity of Granular Porous Media and (II) Experimental Study of the Percolation of Ferrofluid in Porous Media Under a Magnetic Field

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Thursday, April 20, 2023, 4 pm

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ME-EM Graduate Seminar Speaker Series

proudly presents

Radwin Askari, PhD

Geological and Mining Engineering and Sciences
Michigan Technological University


Heat transfer in granular porous media is a crucial problem with significant relevance to various applications, including geothermal reservoirs and enhanced oil recovery through thermal methods. The effective thermal conductivity of such porous materials is strongly influenced by the resistance to flow of heat in the contact area between the grains. Despite its significance, this resistance has been accounted for by a fitting parameter in heat transfer models. However, extensive experiments have shown that the roughness of the grains’ surface follows self-affine fractal stochastic functions. In this study, we investigated the conduction of heat in a packing of particles under compressive pressure, where each grain has a rough self-affine surface. The packing contains a fluid with a given conductivity and is exposed to external pressure. The deformation of the contact area is dependent on the fractal dimension that characterizes the grains’ surface roughness and their Young’s modulus. The results showed that heat transfer increases with increasing pressure. However, for a given compressive pressure, the highest deformation occurs in grains with smoother surfaces and lower Young’s modulus. These findings suggest that the resistance to heat flow in granular porous media is not solely dependent on the packing density but also on the surface roughness of the grains and their mechanical properties.

In the drainage or imbibition of two immiscible fluids in a porous medium, the displacement of fluids can become unstable and form finger-like structures when capillary or viscous forces dominate. Ferrofluids, which are colloidal suspensions of magnetic particles of a few nanometers stabilized in carrier liquids such as water or mineral oil, can be magnetized and aligned with the direction of a magnetic field when a field gradient is applied. Our study demonstrates that using ferrofluids as the transporting medium makes it possible to stabilize fluid displacement in the presence of a magnetic field.


Dr. Radwin Askari is an associate professor in the Department of Geological and Mining Engineering and Sciences at Michigan Tech. He is a geophysicist with a specialization in applied and experimental geophysics. He has a particular interest in studying fluid transport in geological environments and the corresponding geophysical signatures, such as long-period events and volcanic tremors. Dr. Askari is the founder of the Physical Modeling Laboratory (PML) at the Department of Geological and Mining Engineering and Sciences at Michigan Tech (GMES). The PML is equipped with state-of-the-art equipment, including acoustic velocity measurement, low permeability measurement, ultrasonic measurement, and high-speed imaging systems.

Dr. Askari has an impressive track record of obtaining external funding, publishing peer-reviewed journal articles, and teaching experience. He is also the recipient of the prestigious Faculty Early Career Development (CAREER) award from the National Science Foundation. Additionally, Dr. Askari is committed to creating an inclusive and diverse research group that welcomes students from all ethnicities, genders, religions, sexual orientations, and socio-cultural backgrounds.

Invited by: Radheshyam Tewari

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