Ali Akbar Abbasian Arani - Department of machnical engineering, Unive rsity of Kashan, Kashan, Iran.
Moha mmad Hem mat Esfe - Department of machnical engineering, Unive rsity of Kashan, Kashan, Iran.

Research and stu dy about free convection is an essential issue because of its applicatio ns in industry. Some of important applications of free convection include the follo wing: Radio active waste materials disposal [۱] a nd nuclear r eactors cooling [۲].Appli cation of na nofluids inside the cavities has been investigate d by many r esearchers, due to importance of usi ng nanoflui ds to enha nce heat transfer and t herefore effects of different nanofluids parameters such as type of nanofluid, volume fra ction of nanofluid, an d its temperature on heat transfer and stream characteristics has been s tudied. Free convection fluid flow and heat tran sfer of vari ous water ba sed nanofluids in a square cavity w ith an inside thin heater has been in vestigated n umerically by Mahmoo di [۸]. Due to lack of extensive research on nanofluids hea t transfer i nside a cavity with a hot square c ylinder, and also consid ering application this g eometry in industrial application, purpose of this study is to investigate this geome try with re spect to diff erent effective factors like strengt h and weak ness of buo yancy force, type of sus pended particles, and vo lume fracti on of nanoparticles. Res ults of this study are pr esented in th e form of temperature and stream contours and different figures.

Nano fluid, Natura l convectio n, circular c ylinder, Heat transfer