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Experimental Methods in Marine

Hydrodynamics

Lecturer: Professor Sverre Steen

Assistant (lab. tests and lab reports) : Bhushan Taskar

Technicians (lab tests): Torgeir Wahl and Terje Rosten

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Today

• Practical information

• Overview of the subject

• Presentation of hydrodynamic testing facilities worldwide

• Sign up for lab.groups (during the break)

• Tour of our hydrodynamic testing facilities

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Practical Information - lectures

• Lectures: Tuesdays 0815-1000 in T7, with some exceptions!

• Last lecture is Tuesday 7 November

• Lecture notes “Experimental Methods in Marine Hydrodynamics” by

Sverre Steen are found on the web page in the ‘Lecture notes’ sectionhttp://www.ivt.ntnu.no/imt/courses/tmr7/lecture/Kompendium_2014_web.pdf

• Powerpoint presentations and documentation for lab tests will be made

available on the subject web page:

http://www.ivt.ntnu.no/imt/courses/tmr7

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TMR4300, TMR4525, TMR7, and???

• Experimental methods in Marine Hydrodynamics is:

– One half of the subject TMR4300

– A module that you can choose as one of two modules in TMR4525

• You can’t choose both TMR4300 and Experimental Methods as a module!

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Course evaluation

• We need three students that have selected TMR4300, or someone that have chosen both numerical and experimental method for a course evaluation group

• All will get the chance to express their opinion in a ”user survey” in Experimental Methods towards the end

• Please feel free to contact the lecturer if you have suggestions for improvement of the subject

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Access restrictions

• We can’t handle more than approx. 35 students due to

capacity of laboratory exercises

– 6-7 groups with five students in each group

• The course is designed for 5th year Msc students with

knowledge in hydrodynamics similar to TMR4217 Sea

Loads and/or TMR4220 Naval Hydrodynamics

• If access restrictions must be applied, the list of priority is:

1. 5th year Msc students that plan to do experiments for their Msc

thesis

2. PhD students

3. Other final-year Msc students

• Exchange students are not allowed to take final-year

Msc-courses - sorry!

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Examination? Grades?

• The grade is given as a percentage score based on the

delivered lab reports

– Each lab report is graded with a % score

– The lab tests is done in groups. Each group deliver one report.

• For TMR4300 the grade on the A-F scale is calculated

from your average score in the two parts of the subject

• If you take Experimental methods as a module, the the

grade on the A-F scale is calculated from your average

score in the two modules you have selected

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What is an experiment?

An experiment is a procedure carried out to verify, refute, or

validate a hypothesis. Experiments provide insight into cause-

and-effect by demonstrating what outcome occurs when a

particular factor is manipulated. Experiments vary greatly in

goal and scale, but always rely on repeatable procedure and

logical analysis of the results (Wikipedia)

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Objectives of hydrodynamic model tests

• To achieve relevant design data to verify performance of

actual concepts for ships and other marine structures

• Verification and calibration of theoretical methods and

numerical codes

• To obtain a better understanding of physical problems.

• Check a hypothesis

– Example 1: the drag of a cylinder with square cross-section don’t

depend on the Reynolds number

– Example 2: a particular offshore structure is safe and will perform

according to specification

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Objectives of this subject

• Demonstration of different measurement techniques

• Demonstration of different hydrodynamic phenomena

• Demonstration of different typical model tests

• Use of physical experiments in hydrodynamics research

• Understand the importance of experimental uncertainty

analysis

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Rn=10000

Rn=30000

+trip wire

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Flow past a

circular cylinder

- the classical case

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Flow over a backward-

facing step

From http://www.featflow.de/album/catalog/bfs_high_2d/data.html

Velocity

Stream function

Pressure

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Complex flow – turbulence!

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Complex problems

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Model tests for stern ramp on «Stril

Poseidon»

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Real-time hybrid model testing

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Sloshing tests

Calculation of resistance from pressure

distribution

The resistance is calculated as the component in the direction

of travel of the integrated pressure on each panel on the hull

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Why focus on ”model” not ”full scale”

testing?

• Model tests are easier and cheaper to do

• We have high-quality model test facilities available

• Model tests provide a much better control of the

environment Higher quality of data

• Scaling is a problem with model tests

• Special considerations for full scale testing will be covered

in the last lecture

• A rapid increase in instrumentation and measurements on ships in

normal operation means that full scale measurements of this kind will

be more important in the future. We cover such systems briefly.

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Practical information; Lab. tests

• Students are divided in groups for lab. tests 1-4

– Try to group with other students with the same schedule as yours

• Meet at the towing tank main entrance 10 minutes before

the test is scheduled to start

• Each group shall deliver a lab report from each test

– The lab. report shall preferably not be longer than 6 pages +

appendices

– Delivered electronically to Bhushan.taskar@ntnu.no or in his

mail box outside the library

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Score and grading• Each lab report is graded on a scale 0-100.

– Each report counts 1/4 of the total

– All ”authors” of a report gets the same score

• If there are students in your group that refuse to contribute, omit their name

from the report

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It is mandatory to participate in the lab

tests

• If you can’t meet at the scheduled time for your group, try to

switch with another student, or meet with another group just for

the lab exercise

• If you can’t participate in the lab test itself, at least do your part

of the reporting

• If you have an officially valid reason to be absent (for instance

sick leave), the particular lab test will not be included when

calculating your total score

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Reporting lab tests

• The grade is mostly based on the lab-reports, so they are

important

• Follow the requirements and advice given in the exercise text

• There are two example reports on the web page – they are

examples, not ideals and should not be “copied”

• Even though you will probably share the work of analyzing and

writing the reports, it is strongly recommended that all group

members read and check all reports

– We will not accept re-submission of improved reports in case you get poor

score on your first attempt

– We can, in rare cases, ask you to re-submit an improved report if the first

one is clearly insufficient