1 Thi_Qar University Journal for Engineering Sciences, Vol. 3, No. 2 2012 Study of Turbulent Flow and Heat Transfer Over a Backward- Facing Step Under Impingement Cooling Khudheyer S. Mushatet College of Engineering, Thiqar University Nassiriya, Iraq Salimhamed2000@yahoo.com Abstract Computations are presented to study the turbulent flow and heat transfer over a channel backward-facing step under impingement cooling. The problem was simulated for different parameters, such as the number of impinging jets, contraction ratio, size of jets, and jet and channel Reynolds numbers. The contraction ratio had the values 0.25, 0.35 and 0.5. The impinging jets were normal to the cross-channel flow. A control volume approach using staggered grid techniques was considered to integrate the continuity, fully elliptic Navier- Stockes and energy equations. A computer program was developed, and the SIMPLE algorithm was employed to determine the existence of coupling between the continuity and Navier-Stockes equations. The effect of turbulence was modelled using a k-ε model while the wall functions laws were used to treat the regions near the solid walls. The presented results show that the strength and size of recirculation regions near the reattachment region just after the backward-facing step increase as the contraction ratio increases. Also, the results show that the size of jets, number of jets, and jet and channel Reynolds numbers have a significant effect on the flow field, turbulent kinetic energy and variation of the Nusselt number. Keywords: Impingement Cooling, Backward-Facing, Turbulent Flow. فوق عتبة داخل مجرى هوائي بوجود ارة الحرنتقال ابي وااضطرن الجريا اسة ا درد تصادمي تبري مستخلص ال ϢΗ ΚΤΒϟا اάϫ ϲ فاءήΟ أϞاخΩ ϪΒΘ عϕϮ فΓέاήΤϟ اϝΎϘΘϧاϭ ϲΑاήτο اأϥΎϳήΠϟئص اΎμ خΔγاέΪϟ ΔϴΑΎδΣ ΔγاέΩ ΔΒδϧ،ΚفΎϨϤϟ اΩΪعϭ ϢΠΣ ϞΜϣ ϞϣاϮ عΓΪ عήϴΛأΘΑ ΔγϭέΪϤϟ اΔϟأδϤϟ اΔΟάϤϧ ϢΗ .ϲϣΩΎμΘϟ اΪϳήΒΘϟ اΩϮΟϮΑ ϭ ϲائϮϫ ϯήΠϣ ήϟ اϯήΠϤϠϟ ίΪϟϮϨϳέ ϡΎϗέأϭ ήπΤΘϟ اϢϴϗ ΎϬϟ ϥΎϛ ΔγϭέΪϤϟ اήμΨΘϟ اΐδϧ.ΚفΎϨϤϟاϭ ϲδϴ ئ0.25 , 0.3،0.5 ϲϟاϮΘϟ اϰϠ ع ϞϣΎϜΘϟ ΔϔΣاΰϟ اΔϜΒشϟ اΔϴϨϘΗ عϣ ΩΪΤϤϟ اϢΠΤϟ اΔϘϳήρ ΖϣΪΨΘγ. أϲδϴئήϟ اϯήΠϤϟ اϰϠ عΔϳΩϮϤ عΖϧΎϛ ΔϴϣΩΎμΘϟ اΕΎΛΎϔϨϟاϭ