Flow regimes in a vertical Taylor-Couette system with a radial thermal gradient

Abstract

A rich variety of flow regimes in a Newtonian fluid inside a vertical large-aspect ratio and a wide-gap Taylor-Couette system with a radial temperature gradient has been determined in experiments and in direct numerical simulations (DNS). Compared to previous experiments and numerical studies, a wider range of temperature differences (i.e. of the Grashof number Gr) and of the rotation rate (the Taylor number Ta) has been covered. The combined effect of rotation and of the radial temperature gradient is the occurrence of helicoidal vortices or modulated waves at the onset. Stationary axisymmetric vortices are found for very weak temperature differences. A good agreement was found for critical states between results from experiments, linear stability analysis and DNS. Higher instability modes have been determined for a wide range of parameters and a state diagram of observable flow regimes has been established in the plane spanned by Gr and Ta. Some higher states observed in experiments were retrieved in DNS.

Flow dynamics in Taylor–Couette flow reactor with axial distribution of temperature

“…Hence, only a few studies were conducted on the complicated flow patterns. The detailed flow patterns were investigated using numerical simulations and visualization experiments . These studies concluded that a series of various secondary‐flow regimes, induced by the classical axisymmetric Taylor vortices, were observed with the increase in the relative amount of buoyancy.…”

Centrifugal instability of nanofluids with radial temperature and concentration non-uniformity between co-axial rotating cylinders

“…(32)- (35) was solved by the collocation method [45]. Firstly, test computations were performed to validate the numerical code as well as the choice of the trial functions.…”

“…(32)- (35). In this method, the residuals were calculated at the points where the Chebyshev polynomials were equal to zero.…”

“…One should also point out the difference between the left-hand sides of Eqs. (32) and (34), (35), which arises from the different order of the application of the operators D and D * .…”

“…Of course, in the problem at hand, other types of perturbations can arise, for example, helicoidal vortices, etc. [34][35][36][37][38][39][40][41]. Such vortices are also detrimental for the flow stability under conditions of the radial temperature gradient.…”