# hw2 - (e Compare the relative performance of the three...

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Department of Chemical Engineering University of California, Santa Barbara Chemical Engineering 132B Computational Methods in Chemical Engineering Fall 2011 Homework #2 Homework due: Thursday, 6 October 2011 1. Consider the following PVT problem discussed in class. Suppose that one mole of chlorine gas has a pressure of 2 atm and a temperature of 413K. What is the volume of the gas in liters? You may assume the van der Waals equation of state applies, i.e. ± P + an 2 V 2 ² ( V - bn ) = nRT with a = 6 . 29 atm liter 2 /mol 2 and b = 0 . 0562 liter/mol. (a) Plot the EOS as a function of volume and identify the approximate location of all roots. Which root is the physical one? (b) Solve for the ﬂuid volume using the method of bisection to a precision of 5 signiﬁcant ﬁgures, implementing the stopping condition discussed in class. (c) Solve the same problem using Newton’s method to a precision of 5 signiﬁcant ﬁgures, with the initial guess given by the ideal gas law, and with the appropriate stopping condition discussed in class. (d) Repeat (c), but using ﬁxed point iteration.
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Unformatted text preview: (e) Compare the relative performance of the three methods for this problem reporting the approximate error versus iteration number, the order of convergence, and the asymptotic error constant λ . 2. Speedtest. Compare the execution times of the three methods you used in problem 1 (b), (c), and (d) using the MatLab functions tic and toc . Further compare these times with timing for a root obtained from a call to the MatLab function fzero . Can you draw any conclusions regarding the computational eﬃciency of the MatLab built-in functions? 3. Extra Credit – 10pts. Optimize a MatLab code that you write yourself based on any “open method” that starts at the ideal gas volume and ﬁnds the real gas solution to problem 1 with 7 signiﬁcant ﬁgures of precision. Report your execution time and provide the m-ﬁle. The 5 codes with the smallest execution times (on the TA’s computer) will garner extra credit....
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