Comprehensive investigations of mixed convection of Fe–ethylene-glycol nanofluid inside an enclosure with different obstacles using lattice Boltzmann method
Authors: Davood Toghraie
Chenqi Fu
Supat Chupradit
S M Alizadeh
Wanich Suksatan
Amin Rahmani
Majid Zarringhalam
Journal: Scientific Reports (2021)
Discipline: Multidisciplinary
Keywords: Nanofluid; Mixed convection; Square cavity; Adiabatic obstacle; Lattice Boltzmann method
Affiliations: College of Engineering and Technology, Jilin Agricultural University, Changchun, 130118, China. ., Department Mechanical Engineering, Isfahan University of Technology, 84156, Isfahan, Iran., Faculty of Nursing, HRH Princess Chulabhorn College of Medical Science, Chulabhorn Royal Academy, Bangkok, 10210, Thailand., Petroleum Engineering Department, Australian College of Kuwait, West Mishref, Kuwait., Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran, Iran., Department of Occupational Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand., Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran. .

Abstract:  In the present paper, nanofluid mixed convection is investigated in a square cavity with an adiabatic obstacle by using the Lattice Boltzmann method (LBM). This enclosure contains Fe-ethylene-glycol nanofluid and three constant temperature thermal sources at the left wall and bottom of the enclosure through a lateral wall. The fluid is incompressible, laminar, and Newtonian. The obtained results are presented in the constant Ra = 104 and a Pr = 0.71 for different Ri = 0.1, 1, and 10. The effects of the slope of the enclosure, volume fraction of nanoparticles [Formula: see text], the location of adiabatic obstacles, and nanoparticle diameter in the fluid are investigated on the value of heat transfer. A change in the attack angle of the enclosure leads to changes in the movement distance for fluid between hot and cold sources and passing fluid through case E, which affects the flow pattern strongly. In each attack angle, on colliding with an obstacle, the fluid heat transfers between two sources, which leads to uniform heat transfer in the enclosure. By increasing the velocity of the lid, the Richardson number decreases leading to improvement of the convective heat transfer coefficient and Nusselt number enhancement. The results so obtained reveal that by augmenting [Formula: see text] value the effect of Richardson number reduction can augment Nusselt number and the amount of absorbed heat from the hot surface. Consequently, in each state where a better flow mixture and lower depreciation of fluid velocity components, due to the penetration of lid movement and buoyancy force, occurs higher heat transfer rate is accomplished. Furthermore, it is shown that when Ri = 0.1, the effect of cavity angle is more important but when Ri = 10, the effect of the position of obstacle is more visible. 

Retracted: No

PubPeer comments:
 There seems to be re-use of of western blotting data that has been stretched and re-labeled to represent 2 different experiments in figures 1 and 3. There are some bubbles in the western blot that makes it possible to spot the duplicated blots. If you stretch and enhance the contrast the last look identical. Here s the images as they re shown in the paper with the similar lanes in red boxes: https: imgur.com odKB0Yt And here s the same panels after a stretch and contrast adjust. They look remarkably similar. https: imgur.com fhb2XjH , 
 There appears to be another instance of blot re-use and stretching. It involves the same blot shown above in figure 3D and a blot presented in figure 2D. It appears that the same part of the blot in 3D (and in Fig 1A, see above) was stretched and re-labelled. Here s the 2 blots direct from the publication, with the similar part boxed n red: https: imgur.com UjaZqH0 Here s the same two blots with Fig 3D stretched vertically. There are some small imperfections in the blots that makes them identifiable (circled in blue): https: imgur.com tQCkuup Odd that the same blot appears 3 different times labelled as 3 different samples. ,