Axisymmetric Stagnation-Flow Freezing of Saturated Air Vapor

Stagnation flow freezing of saturated air vapor in an axisymmetric cylindrical coordinates system is considered. It covers a detailed discussion on how the ice layer and the ongoing phenomenon changes with time. The fluid along the z-direction, with strain rate  impinges perpendicularly on a substrate flat plate and because of the lower plate temperature than the freezing temperature of the water, condensation has occurred, and then water probably starts to freeze. The flow is assumed laminar with constant properties and the density changes with temperature can be negligible. The momentum equations are converted to an ordinary differential equation by use of appropriate similarity transformations. The obtained ordinary differential equation is solved by using the fourth-order Rung_Kutta Method. Two methods have been used to solve the energy equation: finite-difference numerical techniques and similarity solutions. The results of the energy equations of these two methods are compared together for validation. Based on the obtained results, substrate plate temperature for initiation of water vapor freezing is reduced by the reduction of far-field saturated air temperature. Interestingly, the freezing start time increases with the increase of far-field saturated air temperature first and then reduces rapidly as the increase of the far-field temperature is continued. The ultimate thickness of the ice is also presented. One of the most important achievements of this paper is determining the final thickness of ice in an analytical manner using only the air temperature profile, which can be used as a reliable method to validate the numerical solution.

کلیدواژه ها:

Water vapor freezing ، stagnation flow ، Unsteady Flow ، Viscous Fluid ، Incompressible flow ، Similarity solution ، Ice thickness