کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
160470 | 457080 | 2006 | 8 صفحه PDF | دانلود رایگان |
The onset of hydrodynamical instability induced by impulsive spin-down to rest in a cylinder containing a Newtonian fluid is analyzed by using the propagation theory. The primary transient swirl flow is laminar but for an initially high rotating speed secondary motion sets in at a certain time. It is found here that the critical Reynolds number Rec=320Rec=320, below which the flow is unconditionally stable. For Re>RecRe>Rec the dimensionless critical time τcτc to mark the onset of a fastest growing instability is presented as a function of the Reynolds number Re . Available experimental data and also predictions show that deviation of the velocity profiles from their primary ones occurs starting from a certain time τ≈4τcτ≈4τc. This means that secondary motion is detected experimentally at this characteristic time. It seems that during τc⩽τ⩽4τcτc⩽τ⩽4τc secondary motion is relatively very weak.
Journal: Chemical Engineering Science - Volume 61, Issue 19, October 2006, Pages 6478–6485