جستجوی مقالات مرتبط با کلیدواژه « turbulence » در نشریات گروه « شیمی »

In this paper we continue to study the chaotic properties of the following lattice dynamical system: bji+1= a1 g(bji)+ a2 g(bj-1i)+ a3 g(bj+1i), where i is discrete time index, j is lattice side index with system size L, g is a selfmap on [0, 1] and a1+a2+a3 ∊ [0, 1] with a1+a2+a3=1 are coupling constants. In particular, it is shown that if g is turbulent (resp. erratic) then so is the above system, and that if there exists a g-connected family G with respect to disjointed compact subsets D1, D2, …, Dm, then there is a compact invariant set K'⊆D' such that F |K' is semi-conjugate to m-shift for any coupling constants a1+a2+a3 ∊ [0, 1] with  a1+a2+a3=1, where D' ⊆ IL is nonempty and compact. Moreover, an example and two problems are given.

In this research, the effect of micro turbulence on the flotation rate of quartz particles was investigated. The maximum particle Reynolds number (Rep) was obtained at 60.25 with a particle size of -500+420 µm, impeller speed of 900 rpm, bubble surface area flux of 10.21 1/s and micro scale turbulence size of 162 µm. When the micro turbulence size was equal to the particle size, the maximum flotation rate of coarse particles (Rep>10) was obtained at 1.47 1/min.

Due to high applicability of the fixed bed catalytic naphtha reforming reactors, hydrodynamic features of this kind of reactors with radial flow pattern are improved in this work by utilising computational fluid dynamics technique. Effects of catalytic bed porosity, inlet flow rate and flow regime through the bed on the flow distribution within the system are investigated. It is found that the first reactor among three fixed bed reactors in series is working inappropriately. It is due to the effects of recirculating flow on the hydrodynamics. In addition, flow distribution at the end of each bed is discovered to be non-uniform. By applying computational fluid dynamics technique to the system and manipulating effective parameters, not only vortices are removed at the end of each bed, but also flow distribution through the first reactor is considerably improved. A new internal modification for all reactors is proposed, which allows reactors to become overloaded with the catalyst. Subsequently, inlet flow rate can rise by 10-15 per cent over its current value.