HLRB Project pn56di

Turbulent natural convection of non-Newtonian fluids in enclosed spaces

Institut für numerische Methoden in der Luft- und Raumfahrttechnik, Universität der Bundeswehr München

Turbulent natural convection of non-Newtonian fluids in enclosed spaces

Institut für numerische Methoden in der Luft- und Raumfahrttechnik, Universität der Bundeswehr München

Institut für numerische Methoden in der Luft- und Raumfahrttechnik, Universität der Bundeswehr München

Dr. Yigit Sahin

Werner-Heisenberg-Weg 39

85577 Neubiberg

Natural convection of non-Newtonian fluids (i.e. where the strain rate dependence of shear stresses is non-linear in nature) in enclosed spaces has wide relevance in many engineering applications such as preservation of canned foods, polymer and chemical processing, bio-chemical synthesis, solar and nuclear energy, thermal energy storages. Therefore, the flow and heat transfer knowledge of more complex fluids than Newtonian fluids (fluids like water, air where viscous stress is directly proportional to strain rate) is essential from an engineering perspective since non-Newtonian characters of fluids can also be very useful for designing new adaptive thermal management systems. For example, yield stress fluid is a special type of non-Newtonian fluid, which acts as a solid and does not flow until a threshold stress is surpassed (e.g. anti-drip paints). It is possible to modulate the yield stress based on electrical/magnetic field in electro-rheological/magneto-rheological fluids. Thus, it is possible to eliminate (or alter the strength of) convection by applying a magnetic/electric field, which can be useful for mitigating accidental damage in the case of nuclear meltdown and storage of cryogenic materials. Additionally, shear-thinning (shear-thickening) fluids are another special type of non-Newtonian fluid, which show a decrease (increase) in viscosity with increasing shear rate. Many common man-made and biological fluids exhibit shear-thinning (e.g. ketchup and blood) and shear-thickening (e.g. mixtures of corn starch and water; so-called “bulletproof” custard) behaviour. These types of fluids can also be very useful for augmenting/diminishing heat transfer rates in practical applications such as cooling of electronics, solar and nuclear power systems. Direct Numerical Simulation (DNS) will be conducted to investigate turbulent natural convection of non-Newtonian fluids in enclosures. A detailed parametric analysis will be conducted for providing physical insight into fundamental understanding of aforementioned topic. The outcomes of this project will be useful directly for practical engineering applications.

Impressum, Conny Wendler