## THERMAL SCIENCE

International Scientific Journal

### TRANSIENT CHARACTERISTICS OF COUPLED THERMAL RADIATION AND NATURAL CONVECTION IN A 3-D CYLINDRICAL CAVITY CONTAINING A HEATED PLATE

**ABSTRACT**

In this study, a numerical study of transient combined natural-convection and surface radiation in a cylindrical cavity with a heated plate placed inside is carried out using the open-source platform OpenFOAM. The effects of the Rayleigh number (105 ≤ Ra ≤ 107), inclination angle (0º ≤ φ ≤ 90º), and surface emissivity (0 ≤ ε ≤ 1) on the velocity components, temperature field, and Nusselt number are investigated in detail. Results show that the Rayleigh number has a greater effect on the radiative heat transfer than on natural-convection. Radiative heat transfer increases monotonously with the increase of surface emissivity, and its contribution could be over 50% of the total heat transfer rate. The inclination angle of the plate affects the flow structure, but the difference in total Nusselt number is less than 10% for various inclination angles. Results in this study provide insights into the transient characteristics of coupled thermal radiation and natural-convection in a 3-D cavity and will guide the optimal design of related devices.

**KEYWORDS**

PAPER SUBMITTED: 2022-05-23

PAPER REVISED: 2022-08-09

PAPER ACCEPTED: 2022-08-16

PUBLISHED ONLINE: 2022-09-10

**THERMAL SCIENCE** YEAR

**2023**, VOLUME

**27**, ISSUE

**Issue 3**, PAGES [2377 - 2390]

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