Numerical Study on the Natural Convection of Air in a Cubic Cavity Subjected to a Yawing Motion

Abstract

Natural convections subjected to multi-Degree of Freedom (DoF) motion are much more complex than those in static case, and those subjected to yawing motion are the simplest and ideal case for investigating their characteristics due to less interactive parameters. In this paper, the characteristic of natural convection under yawing motion was studied systematically to clarify the interaction between yawing motion and thermal-dynamic behavior. First of all, the mathematical model was established in a non-inertial coordinate system, and the dimensionless governing equations were derived. Subsequently, the governing equations were discretized in the framework of the finite volume method, and a computer code was developed and validated. After that, the natural convection under yawing motion was calculated with different combinations of dimensionless parameters, and the influence of rotation frequency and amplitude on heat and mass transfer was investigated. It was found that the yawing motion plays a notable role in flow and heat transfer, depending on the relative magnitudes of rotation-induced velocity and buoyancy-induced velocity: At a lower Rayleigh number of 104, the Nusselt number on hot boundary is enhanced by approximately 25% when the rotation period is changed from 12 s to 2 s; while the changing in rotation period from 12 s to 2 s did not induce obvious difference in hot-boundary Nusselt number for a higher Rayleigh number of 105. It is concluded that the vertical-axis harmonic rotation enhances heat transfer if the rotation-induced velocity dominates the flow. The clarification of natural convection characteristic in yawing motion provides convenience for analyzing that in other multi-DoF systems.

Offshore Oil and Gas Safety: Protection against Explosions

“…Mobile offshore drilling units [35][36][37][38] should be preferably certified through a USbased Certified Bodies (ExCB)) using the IECEx protective scheme against explosions because such units will be allowed to operate with minimized additional costs, both in US and EU/EEA's offshore jurisdictions (and very possible worldwide). On the other hand, fixed offshore platforms should be certified strictly following the rules of host countries.…”

Proper Use of Technical Standards in Offshore Petroleum Industry

“…Instead, through the product safety directives, drilling ships and oil and gas equipment onboard has been covered through the International Convention for the Safety of Life at Sea (SOLAS) and more specifically through the Code for the construction and equipment of Mobile Offshore Drilling Units of the International Maritime Organization (the MODU code). The MODU code has been developed to protect any ship as a vessel, and its integrity and stability in the first place in terms of navigation [32][33][34][35], emphasizing the additional requirements caused by drilling activities [36], but does not include requirements for the drilling of subsea wells or the procedures for their control (such drilling operations are subject to control by the coastal state). The MODU code is used in relation to the EU/EEA product safety directives as follows: (1) Protection against explosions; (2) Protection of pressure equipment; (3) Protection of personnel who works with machinery:…”

Three‐dimensional tilted hydromagnetic natural double‐diffusive convection in a rectangular cuboid filled with nanofluids based on magnetic nanoparticles

“…To achieve the best heat transfer in the application, in terms of the porosity of the physical area, a critical nanoparticle volume fraction can be obtained. In addition, there are many studies on heat transfer analysis in cubic cavities, including Sajjadi et al, 11 Sheikholeslami et al, 12 Luo et al, 13 Oztop et al, 14 Zhao et al, 15 Spizzichino et al, 16 Sajjadi et al, 17 Yu et al, 18 and Selimefendigil et al 19 In their research, they analyzed the enhancement of heat transfer in engineering construction, aviation maintenance, central heating, electronics, aviation, lighting industries, and solar systems. Besides cubic cavities, there are numerous studies on nanofluids in other geometries (see, Ujjini Bhojappa and Zeb, 20 Al-Weheibi et al, 21 Ayub et al 22 ) too.…”