Conditions on the Interfacial Surface

Consider a flow of liquid coolant in a capillary where heating and evaporation occur. The conditions on the interface are expressed by means of the continuity of the mass and thermal fluxes and the equilibrium of all acting forces (Landau and Lifshitz 1959)  

Consider a liquid-solid system for which the contact angle is close to 90° (for example, the contact angle for the water-steel system is 70° 0 90° (Grigoriev and Zorin 1982)). The projections of the velocity vector v on x-, y-, z-axes are M = v sin0, v = w = v cos0. For the surface, which is weakly bent, cos 0 C 1 and sin 0 1 we have the following estimate m 2 v = w. Analogously, 

10 Laminar Flow in a Heated Capillary with a Distinct Interface 

Bearing in mind these estimates and the assumptions that T = const., also that the fluid is incompressible, Eqs. (10.2-10.4) transform as follows  

Since the coolant and its vapor are conductive fluids. Toy = TLy = 7, where the subscripts s and f correspond to the saturation parameters and the interface surface, respectively. The saturation pressure and temperature are weakly connected (Sect. 10.9.1), so that Ts is determined practically by the external pressure Pg,oo- 

---