Multiple reference frame approach

The inner-outer (lO) method and the multiple reference frame approach (MRF)... 

For symmetry reasons it was sufficient to model only a part of the domain. The smallest symmetry of the geometry is 60 which contains one impeller blade and one vertical baffle. Two different type of grids were studied. Both grids were refined adaptively. After adaption both grids had about 450 000 cells. Steady state multiple reference frame approach was used in Fluent 5.5 simulations for modelling the rotor rotation in the stationary tank. Standard k-e turbulent model and standard wall functions were used. Simulations were done in liquid (water) phase. 

The Inner-Outer (lO) Method and the Multiple Reference Frame Approach (MRF)... 

FIGURE 10.3 Approaches to modeling flow in stirred reactors, (a) Black box approach, (b) sliding mesh approach, (c) multiple reference frame or inner-outer approach, (d) snapshot approach. 

The first approach is called the multiple reference frame (MRF) or inner-outer approach (inner-outer approach in fact defines inner and outer zones with a finite overlap whereas in the MRF approach there is no overlap between inner and outer regions). In this approach, flow characteristics of the inner region are solved using a rotating framework. These results are used to provide boundary conditions for the outer region (after azimuthal averaging), flow in which is... 

Ranade, V.V, Tayaliya, Y. and Choudhury, D. (1997), Modeling of flow in stirred vessels comparison of snapshot, multiple reference frame and sliding mesh approaches. Presented at 16th NAME Meeting, Williamsberg, June 22-21. 

A 60 sector of the tank was modelled with periodic boundaries on the sides of the sector and symmetric boundary on the top of the tank to describe the free surface. Standard wall functions were employed on all wall boundaries of the computational domain. Huent s multiple reference frame steady state approach was used with k-e turbulence model. Calculation was done in one phase (water). 

The particle tracking-based advective control model described in this chapter is capable of solving two- and three-dimensional plume capture problems with multiple candidate wells and multiple particles in confined and unconfined aquifers. The formulation provides a direct approach to solving plume control problems and uses both forward and reverse particle tracking to exploit numerical characteristics of the two reference frames. 

Another approach mounts either the part or, more commonly, the reference optics on a mechanical translator (shown in yellow in Fig. 5) so that intensity frames can be acquired at a number of intervals (Bruning et al. 1974), typically uniformly spaced by V4. This method, phase shifting, uses multiple intensity frames (minimum 3, typically 7 or more in modem instraments) to solve for the phase modulo 2n at every pixel. Departure of the combined wavefront from its nominal shape over the aperture can be unwrapped provided adjacent pixels have a phase difference less than 2n. 

---