Showing 3 results for Circulation
M. H. Rahimian and M. Farshchi,
Volume 21, Issue 1 (7-2002)
Abstract
The internal flow circulation dynamics of a liquid drop moving in a co- or counter-flowing gas stream has been numerically studied. The present work is concerned with the time accurate numerical solution of the two phase flow field at the low Mach number limit with an appropriate volume tracking method to capture motion and deformation of a liquid drop. It is shown that relative velocity between gas and liquid and the parameters controlling the deformation of the drop have the strongest influence on its internal circulation, too. The effects of the liquid Weber number, ranging from 8 to 32, and of gas stream Reynolds number, ranging from 1 to 20 are studied. It was revealed that the largest and the most lasting internal circulation are observed in drops with small deformation in high Reynolds number gas streams. In the case of counter-flowing gas stream, there is a strong internal circulation inside the liquid drop. The locations of the gas separation points on the drop are strongly influenced by the internal circulation of the drop, resulting in a complex wake dynamics.
Keywords: Numerical solution, Two phase flow, Moving droplet, Droplet internal circulation
M.r. Bannazadeh, A. A. Bidokhti, M. Kherandish and H. F. Hosseini,
Volume 21, Issue 1 (7-2002)
Abstract
Observations of the Caspian Sea during August-September 1995 are used to develop a three-dimensional numerical model to be used in calculating temperature and current. The model has variable grid resolution and horizontal smoothing that filters out small scale vertical motion. Data from the meteorological buoy network on the Caspian Sea are combined with routine observations at first-order synoptic station around the lake to obtain hourly values of wind stress and pressure fields. The hydrodynamic model of the Caspian Sea has 6 vertical levels and a uniform horizontal grid size of 50 km. The model is driven with surface fluxes of heat and momentum derived from observed meteorological data. The model was able to reproduce all the basic features of the thermal structure in the Caspian Sea and larger-scale circulation patterns tended to be anticyclone, with anticyclone circulation within each sub-basin. The results matched observation data.
Keywords: Circulation, Temperature, Numerical model, Vorticity, wind stress
P. Verdi, S. M. Monirvaghefi, F. Ashrafizadeh,
Volume 40, Issue 3 (11-2021)
Abstract
Regarding to the low rate of conventional Ni-P electroless plating method that needs more time to make a coating on the substrate surface, a new technique called “substrate local heating” was introduced based on the temperature parameter modification and its advantages were expressed and compared to the conventional electroless plating technique (temperature=90°C, pH=4.7). In order to provide necessary equipment making this approach practicable, electrical resistance was used as the heating source, and air injection and cooling water circulation were employed to control the solution temperature near the substrate and in the bulk solution, respectively. Considering the heater power (1000 W), the substrate and bulk temperatures were about 190°C and 80°C, respectively. This novel method could enhance the plating rate up to 32 µm/h which was about 60% greater than that of the conventional method, 20 µm/h. Moreover, benefits such as local plating, reduction of production costs, and formation of functionally graded coatings (FGC) can be achieved.
