#*---------------------------------------------------------------------
* EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC.
*
* This LIBRARY is free software; you can distribute it and/or modify
* it under the therms of the ALSOC FREE LICENSE as available at
* http://www.enq.ufrgs.br/alsoc.
*
* EMSO Copyright (C) 2004 - 2007 ALSOC, original code
* from http://www.rps.eng.br Copyright (C) 2002-2004.
* All rights reserved.
*
* EMSO is distributed under the therms of the ALSOC LICENSE as
* available at http://www.enq.ufrgs.br/alsoc.
*
*----------------------------------------------------------------------
* 5. Terminal velocity of falling particles
*----------------------------------------------------------------------
*
*   Description:
*      This problem is part of a collection of 10 representative
*	problems in Chemical Engineering for solution by numerical methods
*	developed for Cutlip (1998).
*
*   Subject:
*       * Fluid Dynamics
*
*	Concepts utilized:
*		Calculation of terminal velocity of solid particles falling in
*	fluids under the force of gravity.
*
*	Numerical method:
*		* Single nonlinear algebraic equation
*
*   Reference:
*       * CUTLIP et al. A collection of 10 numerical problems in 
*	chemical engineering solved by various mathematical software 
*	packages. Comp. Appl. in Eng. Education. v. 6, 169-180, 1998. 
*       * More informations and a detailed description of all problems
*	is available online in http://www.polymath-software.com/ASEE
* 
*----------------------------------------------------------------------
* Author: Rodolfo Rodrigues
* GIMSCOP/UFRGS - Group of Integration, Modeling, Simulation, 
*					Control, and Optimization of Processes
* $Id$
*--------------------------------------------------------------------*#
using "types";



Model problem
	PARAMETERS
	g		as acceleration	(Brief="Accelaration of gravity", Default=9.80665);
	
	
	VARIABLES
	vt		as velocity		(Brief="Terminal velocity");
	rho_p	as dens_mass	(Brief="Particle density");
	rho		as dens_mass	(Brief="Fluid density");
	Dp		as length		(Brief="Diameter of the spherical particle", Lower=1e-6);
	CD		as Real			(Brief="Dimensionless drag coefficient", Lower=1e-6); # 1e-9
	Re		as Real			(Brief="Reynolds number", Lower=1e-6); # 1e-9
	mu		as viscosity	(Brief="Viscosity", DisplayUnit='kg/m/s');
	
	
	EQUATIONS
	"Force balance"
	vt = sqrt(4*g*(rho_p - rho)*Dp/(3*CD*rho));
	
	"Reynolds number"
	Re = (Dp*vt*rho)/mu;


	if Re < 0.1 then
	"Drag coefficient"
		CD = 24/Re; # Re < 0.1
		else if Re <= 1e3 then
		"Drag coefficient"
			CD = (24/Re)*(1 + 0.14*Re^0.7); # 0.1 =< Re =< 1000
			else if Re <= 3.5e5 then
			"Drag coefficient"
				CD = 0.44; # 1000 < Re =< 3.5e5
			else
			"Drag coefficient"
				CD = 0.19 - 8e4/Re; # 3.5e5 < Re
			end
		end
	end
end


FlowSheet solution
	DEVICES
	vel		as problem;
	
#* 	Hard convergence to 30*g!
	It needs to change the limits of CD and Re.
	Try to change lower limits to 1e-9.			*#
	
#	SET
#	vel.g = 30*(9.80665*'m/s^2'); # Problem b
	
	
	SPECIFY
	vel.rho_p = 1800*'kg/m^3';
	vel.Dp = 0.208e-3*'m';
	vel.rho = 994.6*'kg/m^3'; # at 298.15*'K'
	vel.mu = 8.931e-4*'kg/m/s'; # at 298.15*'K'
	

	OPTIONS
	Dynamic = false;
end