## THERMAL SCIENCE

International Scientific Journal

### THE EFFECT OF SURFACTANT SOLUTIONS ON FLOW STRUCTURES IN TURBULENT RAYLEIGH-BENARD CONVECTION

**ABSTRACT**

This paper presents an experimental study on the flow structures in turbulent Rayleigh-Bénard convection with surfactant solutions. The shadowgraph visualization was used to obtain the plumes and the velocity field was measured using particle image velocimetry. The results show that the size of plumes in surfactant solution case is larger than that in Newtonian fluid case and it needs more time for surfactant solution case to start convection. The large-scale circulation fails to form in surfactant solution case and the convection velocity is smaller. A decrease of the measured Nusselt number is observed in surfactant solution case. The above phenomena are caused by the shear-shinning and elastic chara cteristics of surfactant solution.

**KEYWORDS**

PAPER SUBMITTED: 2017-10-26

PAPER REVISED: 2017-11-23

PAPER ACCEPTED: 2017-11-23

PUBLISHED ONLINE: 2017-12-23

**THERMAL SCIENCE** YEAR

**2018**, VOLUME

**22**, ISSUE

**Supplement 2**, PAGES [S507 - S515]

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