COMPUTATIONAL ENGINEERING

Academic year 2006-2007; Class: 4th block, Wednesday 11:15 - 13:00

The subject of the course is the dynamic behaviour of liquids with a free surface; emphasis ison modelling and simulation. The course will be carried out in the form of projects, wherestudents will be asked to investigate practical engineering problems. Weekly classes will providebackground theory.

Project description

In the 2006-2007 course in Computational Engineering a number of engineering applicationswhere free-surface flow plays a dominant role will be studied. The case studies come from threedifferent engineering disciplines:– Marine Engineering: influence of liquid sloshing in cargo tanks onboard LNG tank ships;– Space Technology: influence of liquid sloshing on the dynamics of spacecraft;– Earthquake Engineering: oscillation suppression in tall buildings through tuned liquid dampers

(TLD).

The projects consist of several aspects:

• Literature studyWhat is the engineering relevance of the case study? Which type of approaches are in use(modelling at various levels of sophistication)?

• Selection of testcasesSearch in the literature for (simple) cases that can be used for either analytical investigationor for numerical simulation. I.e. they should be simple enough, sufficiently documented,and validation material (either through experiments or numerical simulation) should beavailable.

• Investigation by analytical and numerical toolsCarry out the investigation on various modelling levels. Formulate the equations of mo-tion (e.g. pendulum analogy, potential theory or Navier-Stokes) and boundary conditions.Identify simplified situations where analytical theory (‘pencil and paper’) can be used;distinguish between sloshing on earth and sloshing in space. Describe numerical methods(CFD) to solve the equations of motion.

• Verification and validation of simulation resultsMake sure that the numerical simulation results may be looked at with a physical eye, i.e.numerical errors should be sufficiently small. In other words: Have I done the job right?Compare the outcome of the analytical and numerical studies with results of analysis,experiments or other numerical simulations. In other words: Have I done the right job?

• Preparation of deliverablesPrepare oral and written reports, at several moments during the project: projectplan,intermediate progress reports, final report.

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Project organisation

The projects are to be carried out in groups of 2-4 students: the projectteam. Identify subtasksand divide them between the projectteam members. Several subtasks can be imagined, suchas:– literature study on engineering background;– literature study on analytical approaches;– literature study on mechanical models;– literature study on numerical approaches;– slosh predictions from analytical theory;– application of mechanical models;– familiarisation with the simulation tool ComFlo (see below);– preparation of the input for the simulations;– slosh predictions by numerical means;– validation of the various models used;– writing of subreports for the above subtasks;– combining subreports into one overall report.

Many other aspects should be taken into account, such as:– Who takes care of the coordination within a projectteam?– Who is responsible for subtasks?– Is there any knowledge to share with other projectteams?

The largest challenge in the project will be ‘time’. The project should be finished within thecurrent teaching block: “design to cost”.Keep track of the amount of hours you are spending on the project.

Final deliverable

At the end of the project a document should be prepared that contains the following informa-tion:– problem description, engineering relevance;– available expertise and data (from experiments or simulations);– description of various levels of modeling;– theoretical predictions (various levels);– discussion of results;– recommendations for further research.

Further, an oral presentation has to be held by each projectteam.

Available material

• Flyers (obtained from internet) introducing the case studies will be handed out.

• For analytical info on sloshing see e.g.

– A.R. Paterson. A first course in fluid dynamics. Cambridge University Press, 1983.Chapter XIII.

• A general review paper is:

– R.A. Ibrahim, V.N. Pilipchuk and T. Ikeda. Recent advances in liquid sloshing dy-namics. Appl. Mech. Rev. 54(2), 2001, pp. 133–199. In particular Chapter III,

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“Equivalent mechanical models,” pp. 147–150. Cannot be downloaded; copy avail-able from the docent.

• More specific information including testcases can be found in the following papers.

– For LNG tanks:A. Cariou and G. Casella. Liquid sloshing in ship tanks: a comparative study ofnumerical simulation. Marine Structures 12 (3), 1999, pp. 183–198.V. Armenio and M. La Rocca. On the analysis of sloshing of water in rectangularcontainers: numerical study and experimental evaluation. Ocean Engineering 23 (8),1996, pp. 705–739.M. Serdar Celebi and H. Akyildiz. Nonlinear modeling of liquid sloshing in a movingrectangular tank. Ocean Engineering 29, 2002, pp. 1527–1553.

– For sloshing in space:W. Teichert and M. Klein. The dynamic behaviour of fluids in microgravity. ESABulletin 85, February 1996. Available at:http://esapub.esrin.esa.it/bulletin/bullet85/klein85.htm

P.J. Enright and E.C. Wong. Propellant slosh models for the Cassini spacecraft.Paper AIAA-94-3730-C, 1994. Photocopy available from the docent.H.N. Abramson. The dynamic behaviour of liquids in moving containers, NASA SP-106, 1966. In particular Chapter 11.4 “Low-g sloshing and some related problems.”Photocopy available from the docent.

– For tuned liquid dampers (TLD):D. Reed, J. Yu, H. Yeh and S. Gardarsson. Investigation of tuned liquid dampersunder large amplitude excitation. J. Engineering Mechanics 124 (4), 1998, pp. 405–413.S. Gardarsson, H. Yeh and D. Reed. Behaviour of sloped-bottom tuned liquiddampers. J. Engineering Mechanics 127 (3), 2001, pp. 266–271.D.E. Olson and D.A. Reed. A nonlinear numerical model of the sloped bottom tunedliquid damper. In: 8th ASCE Speciality Conference of Probabilistic Mechanics andStructural Reliability, paper PMC2000-030. Downloadable from:www.usc.edu/dept/civil eng/johnsone/pmc2000/sessions/papers/p030.pdf

The referred journals (and many more) are on-line available throughwww.rug.nl/bibliotheek/catalogibestanden/elektijdschr/ejournalsoverzichtalf.

• A global theoretical background on simulation methods for free-surface flow can be foundin chapter 5 of the lecture notes Numerieke Stromingsleer (Dutch version – no longeravailable). This chapter will be handed out.

• The in-house-developed computation method ComFlo for the simulation of free-surfaceflow, including documentation, will be made available. The input file provided correspondswith Test 1.1 of Cariou and Casella (1999).

• Examples of calculations with ComFlo, and its two-dimensional predecessor Savof96,can be found at our website www.math.rug.nl/∼veldman/cfd-gallery.html

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