Computational fluid dynamics modelling

Computational Fluid Dynamics modelling predictions (Al-Rashed etal., 1996) indicate that such velocity gradients can vary considerably throughout a vessel, as illustrated in Figure 8.28. 

Kelly, A. A., Examination of smoke movement in a two-story compartment using salt water and computational fluid dynamics modeling, MS Thesis, Department of Fire Protection Engineering, University of Maryland, College Park, Maryland, 2001. 

As mentioned earlier, reformate from a fuel processor often needs addition processing to reduce the carbon monoxide levels. Researchers at the Stevens Institute of Technology are developing a microscale preferential oxidation (FrOx) reactor to decrease the carbon monoxide level in the reformate stream to below 100 ppm. As part of their research, they used advanced computational fluid dynamic modeling. 

McCarthy LG, Kosiol C, Healy AM, Bradley G, Sexton JC, Corrigan OI. Simulating the hydrodynamic conditions in the United States Pharmacopeia paddle dissolution apparatus. AAPS Pharm Sci Tech 2003 4(2) Article 22. McCarthy LG, Bradley G, Sexton JC, Corrigan OI, Healy AM. Computational fluid dynamics modeling of the paddle dissolution apparatus agitation rate, mixing patterns, and fluid velocities. AAPS Pharm Sci Tech 2004 5(2) Article 31. 

Figure 12.4 Mastering column distribution design. On the left-hand side are shown computational fluid dynamic modeling results, and on the right-hand side are displayed pictures of the stationary phase cross section after an experiment with a dye (flow goes from the bottom to the top) (a) without a distributor, and (b) with a correctly designed distributor.

The effects deriving from both nonideal mixing and the presence of multiphase systems are considered, in order to develop an adequate mathematical modeling. Computational fluid dynamics models and zone models are briefly discussed and compared to simpler approaches, based on physical models made out of a few ideal reactors conveniently connected. 

Index Entries Screw reactor computational fluid dynamics modeling backflow hydrolysis. 

Computational fluid dynamic models (CFD) Computational models of fluid flow based on numerical solution of the continuity and Navier-Stokes equations (in either instantaneous or, more commonly, some type of averaged form). 

Tiwari P, Antal SP, Burgoyne A, Belfort G, Podowski MZ (2004) Multifield computational fluid dynamics model of particulate flow in curved circular tubes. Theoret Comput Fluid Dynamics 18 205-220... 

Figure 4-18. Computational fluid dynamics modeling of a horizontal reactor with cyclindrical symetry. (Courtesy of G. Evans and Verlan Gabrielson, Sandia National Laboratory).

Estimating the size of the smallest length scale is relatively simple. One could use computational fluid dynamic modeling techniques or estimate them based on the power input to the system (head loss) and the mass of the fluid being powered. For example, in pipe flow, the energy dissipation rate is a function of the total head loss in the flow h, the volumetric flow rate Q, the density of the solution p, and the mass of the solution m, which in this case is the mass of fluid contained within the pipe [Equation (4.1-3)]... 

Strain-Rate Estimates in the Stir Zone. Strain rates during FSW have not been measured experimentally. However, several modeling techniques have been used to estimate the strain rates during FSW of aluminum alloys, including a kinematic approach (Ref 8), CTH or hydrocode (Sandia National Laboratories) (Ref 9), computational fluid dynamics models (Ref... 

Fig. 10.8 Effect of interfacial boundary conditions on the predicted flow from a two-dimensional computational fluid dynamics ° model with a profiled tool, (a, b) Velocity vectors and the boundary at which the effective strain rate is 2 s b (c, d)...

Fig.10.9 Example of two-dimensional tool profiles tested by computational fluid dynamics modeling. Source Ref 45-47, 50...

Fig. 1 0.11 Predicted particle tracks through multiple revolutions of a Triflat tool from a two-dimensional computational fluid dynamics model. The cumulative number of revolutions (n) in each case is indicated. Adapted from Ref 47...

Fig. 1 0.1 2 Predicted streamlines for a three-dimensional computational fluid dynamics model using interfacial slip for (a) a Tri-° flute tool and (b) a Trivex tool. Adapted from Ref 28...

Langrish, T. A. G. and Kockel, T. K. 2001. The assessment of a characteristic drying curve for milk powder for use in computational fluid dynamics modeling. Chem. Eng. J. 84 69-74. 

Huang, L.X., Kumar, K., and Mujumdar, A.S., Simulation of a spray dryer fitted with a rotary disk atomizer using a three dimensional computational fluid dynamic model, Drying TechnoL, 2004, 22(6), 1489-1515. 

Improvements in compressor efficiency have also had a significant effect. In an interesting example of technology cross-fertilization, much of the improvement in compressor efficiency has been driven by advances in computational fluid dynamic modeling. 

Wiley DE, Fletcher DF (2003) Techniques for computational fluid dynamics modelling of flow in membrane channels. J Membr Sci 211(1) 127-137... 

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