Agnahreyfingar í iðustreymi drifið með varmaburði
Fréttatilkynning verkefnisstjóra
The main findings include a new and improved Logarithmic Law of the Wall model for the velocity profile in convective channel flow and phenomenological models for the evolution of the Nusselt number as a function of Reynolds number and Rayleigh number in a mixed convective flow.
Thermal convection pays an important role in a variety of environmental and industrial flows. These flows occur where thermal stratification or temperature differences are present, and result in either amplification or quenching of turbulence depending on weather the stratification is stable or unstable. For sufficiently high stratification, buoyancy forces may alter the turbulent flow field significantly, and result for example in an altered boundary layer dynamics close to solid boundaries. Stable stratification is for example known to inhibit the bursting phenomenon, by depleting the transport of turbulent fluctuations from the wall, thus reducing the turbulent drag at the wall.
Heiti verkefnis: Agnahreyfingar
í iðustreymi drifið með varmaburði / Lagrangian dynamics in convective
turbulence
Verkefnisstjóri: Ármann Gylfason, Háskólanum í Reykjavík
Tegund styrks: Verkefnisstyrkur
Styrkár: 2012-2014
Fjárhæð styrks: 19,98 millj. kr. alls
Tilvísunarnúmer Rannís: 12002102
In this work, we have
primarily worked on the case of turbulence in the presence of unstably
stratified thermal field. We have investigated a large range of flow
parameters, both in terms of the turbulent Reynolds number, but also in terms
of the thermal forcing, namely the Rayleigh number. We have applied both
Eulerian and Lagrangian techniques to propose new and original models aimed at describing
important physical aspects of a subsets of these flows.
Our main findings include a new and improved Logarithmic Law of the Wall model for the velocity profile in convective channel flow and phenomenological models for the evolution of the Nusselt number as a function of Reynolds number and Rayleigh number in a mixed convective flow. Additionally we have provided a new insight into the structure of such flows, and provided spatial and temporal correlations and estimates of important scales of motions and thermal properties.
This work has resulted in the development of a high-resolution, thermal Lattice Boltzman algorithm. A new experimental facility has been implemented, designed for optical measurements of mixed convective flows. The work has furthermore resulted in a pending Ph.D. thesis, one masters thesis, two papers in highly relevant ISI scientific journals, as well as in 10 conference publications.
