Modeling gravitational effects

Two common types of one-dimensional flow regimes examined in interfacial studies Poiseuille and Couette flow [37]. Poiseuille flow is a pressure-driven process commonly used to model flow through pipes. It involves the flow of an incompressible fluid between two infinite stationary plates, where the pressure gradient, Sp/Sx, is constant. At steady state, ignoring gravitational effects, we have... 

Annular. When the vapor velocity is high enough (j > 1.5), gravitational effects can be neglected, and the condensate collects as a thin annular film around the inside of the tube walls, with no stratification. A significant portion of most condensers operate in this flow regime. There are numerous predictive models described in the literature for annular flow. Laminar flow models predict heat transfer coefficients that are too low, and turbulent models must be used. The most commonly used models are listed in Table 14.1. All models have a form for the local Nusselt number... 

Apart from aerodynamic resistances and gravitational effects, all external forces acting on a vehicle are applied through the wheels. Consequently, total vehicle control will entail the application of control action at the wheels, and will be based on a combination of propulsion, steering and suspension control. Therefore it is necessary to develop vehicle models which are capable of representing all these actions simultaneously. 

The neck-down profile and the speed during fibre drawing process have been modelled and examined by solving the mass and momentum conservation equations of a two-dimensional axial-symmetric cylinder with varying the radius. This model includes gravitational effects in a vertically drawn fibre [428]. 

This postulate imposes an idealization, and is the basis for all subsequent property relations for PVT systems. The PVT system sei ves as a satisfactoiy model in an enormous number of practical applications. In accepting this model one assumes that the effects of fields (e.g., elec tric, magnetic, or gravitational) are negligible and that surface and viscous-shear effects are unimportant. 

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