AFDM: An Advanced FluidDynamics Model
Abstract
This report consists of three parts. First, for the standard Advanced FluidDynamics Model (AFDM), heattransfer coefficients between components are worked out, depending on the different possible topologies. Conduction, convection, and radiative heattransfer mechanisms are modeled. For solid particles, discontinuous phases that obey a rigid model, and components lacking relative motion, heat transfer is by conduction. Convection is represented for fluids in motion inside circulating bubbles and/or droplets. Radiation is considered between droplets in vapor continuous flow. In addition, a filmboiling model has been formulated, where radiation provides the lower limit on the fueltocoolant heattransfer coefficient. Second, the momentumexchange coefficients are defined for the standard AFDM. Between a continuous and discontinuous phase, the model consists of both laminar and turbulent terms. The most important feature is the drag coefficient in the turbulent term. It is calculated by a drag similarity hypothesis with limits for large Reynolds numbers, distorted particles, and churnturbulent flow. A unique hysteresis algorithm exists to treat the liquid continuous to vapor continuous transition. Two discontinuous components are coupled using a turbulent term with an input drag coefficient. Fluid structure momentum exchange is represented with a standard frictionfactor correlation. Third, the formulas used for the AFDM simplified Step 1 models are discussed. These include the heattransfer coefficients, the momentumexchange functions, and the manner in which interfacial areas are determined from input length scales. The simplified modeling uses steadystate engineering correlations, as in SIMMERII.
 Publication:

Unknown
 Pub Date:
 September 1990
 Bibcode:
 1990afdm.reptR....B
 Keywords:

 Computer Programs;
 Fluid Dynamics;
 Fluid Flow;
 Hysteresis;
 Turbulent Heat Transfer;
 Algorithms;
 Convection;
 Drag;
 Momentum Transfer;
 Phase Transformations;
 Reynolds Number;
 Fluid Mechanics and Heat Transfer