Turbulent thermal convection of viscoelastic fluids

• Applicant: Dr. Jiaxing Song
• Subject Area: Fluid Mechanics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559832532

Turbulent thermal convection is a widespread phenomenon observed in the fluid cores of stars and planets, planetary atmospheres, terrestrial oceans, and industrial processes. The complex turbulent flow motions, including plume jets and large-scale winds, and the heat transfer in thermal convection have been well studied for Boussinesq Newtonian fluids over the past 50 years. While all but a few common liquids and gases, such as water and air, can be assumed to be Newtonian for practical calculations under normal conditions, most real fluids in nature and industry are viscoelastic, i.e. they often exhibit both solid-like (assumed to be elastic) and fluid-like (viscous) behaviour. Examples include the petroleum and magma beneath the Earth's surface, many polymer solutions, molten polymers, many solid suspensions, blood and most highly viscous fluids. However, studies of the turbulent thermal convection of viscoelastic fluids are rare. The lack of experimental techniques for in situ measurement of elastic stresses severely limits the much needed mechanistic understanding of turbulent dynamics in viscoelastic flow. To study the heat transfer process and turbulence dynamics of thermal convection of viscoelastic fluids, I propose to perform direct numerical simulations of viscoelastic turbulent Rayleigh--Bénard convection with and without system rotation in both periodic and confined cells; the later for direct comparison with other available experiments. The role of fluid viscoelasticity in heat and momentum transport and the changes in coherent flow structures under different thermal driving forces, rotation intensities and mechanical boundary conditions will be investigated. The study of the flow behaviour of viscoelastic thermal convection is crucial for optimising the design and efficiency of industrial processes involving heat transfer, and for understanding geophysical phenomena and environmental processes under more realistic conditions.

• DFG Programme: Research Grants
• Co-Investigator: Privatdozentin Dr. Olga Shishkina