Vol.6, No 1, 2008 pp. 25 - 36
UDC
536.24
EFFECT OF WALL-MOUNTED OBSTACLES ON CONVECTIVE HEAT TRANSFER IN THE POISEULLE–BENARD CHANNEL
Mohammad Javad Hosseini, Mousa Farhadi, Kurosh Sedighi
School of Mechanical Engineering, Babol Noshirvani University of Technology, P.O.Box 484
Babol, Mazandaran, Islamic Republic of Iran
E-mail: mfarhadi@nit.ac.ir
Abstract.
In this study, the mixed convection heat transfer and the fluid flow in the Poiseulle–Benard Channel with wall-mounted obstacles were investigated numerically. The classic Boussinesq incompressible approximation was employed for buoyancy effect while the UTFN [Nourollahi 2007] code was used to solve the momentum and energy equations. This code was generated for solving the energy and momentum equations in the non-orthogonal grids using the Finite Volume method and the SIMPLE algorithm to discretize the equations of fluid and resolving the pressure-velocity coupling system, respectively. The Convection and Diffusion term of the equations are discretized by the Central Difference Scheme (CDS). There is a possibility for producing check board pressure due to the use of collocated grid and the central difference scheme for discretizing the Convection and Diffusion terms. To avoid of this problem, the Raio-Chow interpolation has been used. In this study the Reynolds, Prandtl and Rayleigh numbers were fixed at 10, 0.7 and 104 respectively. In this study the effect of the wall-mounted obstacles on the flow field and heat transfer at the Poiseulle–Benard channel was studied. The number of obstacles was changed from 1 to 3 over each wall. The results show that the local Nusselt number distribution changes very sharply near the obstacles over the wall of the channel. With the increase of the number of obstacles, the mean Nusselt number increases. The arrangement of the obstacle has a small effect on the mean and local Nusselt number.
Key Words:
Mixed Convection, Poiseulle–Benard Channel, Wall-mounted Cubes.
UTICAJ ZIDNO-MONTIRANIH PREPREKA NA STRUJNI PRENOS TOPLOTE U POAZEJ-BENAROVOM KANALU
U ovom istraživanju numerički se ispituje mešovito strujanje prenosa toplote i prolaska fluida u Poazej-Benarovom kanalu sa zidno-montiranim preprekama. Klasična Boussinesq-ova nestišljiva aproksimacija je korišćena za efekat potiska a UTFN (Nurolahi 2007) kod se koristio za rešavanje jednačina momenta i energije. Ovaj kod je razvijen za rešavanje jednačina momenta i energije kod ne-orthogonalnih rešetki uz pomoć metode konačnih elemenata i algoritma SIMPLE za diskretizaciju jednačina fluida i rešavanje sprežnih sistema pritisak-brzina, respektivno. Članovi za strujanje i difuziju jednačina diskretizuje se šemom središne razlike ili CDS-om. Postoji mogućnost stvaranja pritiska kontrolne table usled korišćenja kolokirane rešetke i šeme središnje razlike za diskretizaciju članova za strujanje i difuziju. Kako bi se izbegao ovaj problem korišćena je Raio-Čou interpolacija. U ovoj studiji Rejnoldsovi, Prandtlovi i Rejlijevi brojevi su fiksirani na 10, 0.7 i 10 4 , respektivno. U ovoj studiji pročava se efekat zidno-montiranih prepreka na protok fluida i prenos toplote u Poazej-Benarovom kanalu. Broj prepreka se menjao sa 1 na 3 nad svakim zidom. Rezultati pokazuju da se lokalni Nuseltov broj distribucije menja vrlo jako blizu prepreka iznad zida kanala. Sa povećanjem broja prepreki, povećava se i srednji Nuseltov broj. Raspored prepreki ima mali uticaj na srednji lokalni Nuseltov broj.
Ključne reči:
Mešovito strujanje, Poazej-Benardov kanal, Zidno-montirane kocke
