1 | #*--------------------------------------------------------------------- |
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2 | * EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC. |
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3 | * |
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4 | * This LIBRARY is free software; you can distribute it and/or modify |
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5 | * it under the therms of the ALSOC FREE LICENSE as available at |
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6 | * http://www.enq.ufrgs.br/alsoc. |
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7 | * |
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8 | * EMSO Copyright (C) 2004 - 2007 ALSOC, original code |
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9 | * from http://www.rps.eng.br Copyright (C) 2002-2004. |
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10 | * All rights reserved. |
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11 | * |
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12 | * EMSO is distributed under the therms of the ALSOC LICENSE as |
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13 | * available at http://www.enq.ufrgs.br/alsoc. |
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14 | * |
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15 | *---------------------------------------------------------------------- |
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16 | * 5. Terminal velocity of falling particles |
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17 | *---------------------------------------------------------------------- |
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18 | * |
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19 | * Description: |
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20 | * This problem is part of a collection of 10 representative |
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21 | * problems in Chemical Engineering for solution by numerical methods |
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22 | * developed for Cutlip (1998). |
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23 | * |
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24 | * Subject: |
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25 | * * Fluid Dynamics |
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26 | * |
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27 | * Concepts utilized: |
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28 | * Calculation of terminal velocity of solid particles falling in |
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29 | * fluids under the force of gravity. |
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30 | * |
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31 | * Numerical method: |
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32 | * * Single nonlinear algebraic equation |
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33 | * |
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34 | * Reference: |
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35 | * * CUTLIP et al. A collection of 10 numerical problems in |
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36 | * chemical engineering solved by various mathematical software |
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37 | * packages. Comp. Appl. in Eng. Education. v. 6, 169-180, 1998. |
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38 | * * More informations and a detailed description of all problems |
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39 | * is available online in http://www.polymath-software.com/ASEE |
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40 | * |
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41 | *---------------------------------------------------------------------- |
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42 | * Author: Rodolfo Rodrigues |
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43 | * GIMSCOP/UFRGS - Group of Integration, Modeling, Simulation, |
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44 | * Control, and Optimization of Processes |
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45 | * $Id$ |
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46 | *--------------------------------------------------------------------*# |
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47 | using "types"; |
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48 | |
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49 | |
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50 | |
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51 | Model problem |
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52 | PARAMETERS |
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53 | g as acceleration (Brief="Accelaration of gravity", Default=9.80665); |
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54 | |
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55 | |
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56 | VARIABLES |
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57 | vt as velocity (Brief="Terminal velocity"); |
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58 | rho_p as dens_mass (Brief="Particle density"); |
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59 | rho as dens_mass (Brief="Fluid density"); |
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60 | Dp as length (Brief="Diameter of the spherical particle", Lower=1e-6); |
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61 | CD as Real (Brief="Dimensionless drag coefficient", Lower=1e-6); # 1e-9 |
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62 | Re as Real (Brief="Reynolds number", Lower=1e-6); # 1e-9 |
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63 | mu as viscosity (Brief="Viscosity", DisplayUnit='kg/m/s'); |
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64 | |
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65 | |
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66 | EQUATIONS |
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67 | "Force balance" |
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68 | vt = sqrt(4*g*(rho_p - rho)*Dp/(3*CD*rho)); |
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69 | |
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70 | "Reynolds number" |
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71 | Re = (Dp*vt*rho)/mu; |
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72 | |
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73 | |
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74 | if Re < 0.1 then |
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75 | "Drag coefficient" |
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76 | CD = 24/Re; # Re < 0.1 |
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77 | else if Re <= 1e3 then |
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78 | "Drag coefficient" |
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79 | CD = (24/Re)*(1 + 0.14*Re^0.7); # 0.1 =< Re =< 1000 |
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80 | else if Re <= 3.5e5 then |
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81 | "Drag coefficient" |
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82 | CD = 0.44; # 1000 < Re =< 3.5e5 |
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83 | else |
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84 | "Drag coefficient" |
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85 | CD = 0.19 - 8e4/Re; # 3.5e5 < Re |
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86 | end |
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87 | end |
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88 | end |
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89 | end |
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90 | |
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91 | |
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92 | FlowSheet solution |
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93 | DEVICES |
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94 | vel as problem; |
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95 | |
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96 | #* Hard convergence to 30*g! |
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97 | It needs to change the limits of CD and Re. |
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98 | Try to change lower limits to 1e-9. *# |
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99 | |
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100 | # SET |
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101 | # vel.g = 30*(9.80665*'m/s^2'); # Problem b |
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102 | |
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103 | |
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104 | SPECIFY |
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105 | vel.rho_p = 1800*'kg/m^3'; |
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106 | vel.Dp = 0.208e-3*'m'; |
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107 | vel.rho = 994.6*'kg/m^3'; # at 298.15*'K' |
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108 | vel.mu = 8.931e-4*'kg/m/s'; # at 298.15*'K' |
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109 | |
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110 | |
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111 | OPTIONS |
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112 | Dynamic = false; |
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113 | end |
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