Scaling and temperature profiles in turbulent Rayleigh-Bénard convection EuHIT Funded Project

Team

Jakub Drahotský
The Czech Academy of Science, Brno, Czech Republic
Ronald du Puits
Technische Universitaet Ilmenau, Ilmenau, Germany
Michal Macek
The Czech Academy of Sciences, Brno, Czech Republic
Vera Ludmila Musilova
Institute of Scientific Instruments of the CAS, v. v. i., Brno, Czech Republic

Overview

Research Infrastructure
Barrel of Ilmenau, Germany
Facilities used
Barrel of Ilmenau (BOI)
Project leader
Pavel Urban
The Czech Academy of Sciences, Brno, Czech Republic

Abstract

The principal motivation of this project is to shed light on discrepancies among published results on Rayleigh-Bénard convection (RBC) around Ra number 1e11 in Nu(Ra) and Re(Ra) scaling laws and influence of non Oberbeck-Boussinesq (NOB) effects on RBC, especially on a possible transition of RBC to the ultimate regime. It was observed experimentally that NOB effects do indeed lead to asymmetry of the boundary layers, which subsequently alters the heat transfer efficiency at high Ra. To appreciate NOB effects we will focus on measurement of the vertical temperature profiles in Oberbeck-Boussinesq (OB) and NOB case of room temperature air across the cylindrical cell with aspect ratio G=1. We will also attempt to understand the observed asymmetry of the boundary layers for various fluids in nearly OB case and different sign of this asymmetry in NOB case. The experiment will take place in the Barel of Ilmenau (TU Ilmenau) which is newly equipped with a technique using the fiber-optic temperature measurement system LUNA ODISI B (Optical Distributed Sensor Interrogator) for temperature profiles measurements. The system permits to measure the temperature along a very thin glass fiber and seems to be perfectly suited to measure vertical profiles in the Barrel of Ilmenau. NOB effects on temperature profiles and consequences on Nu(Ra) and Re(Ra) scalings will be analysed and compared with experimental results performed in Brno using the Czech Cryogenic Turbulent Facility-3 (CCTF-3).