Data Storage Report. Author: Jamie Luxmoore, Lancaster University, UK

Transcription

1 Data Storage Report Experimental investigation of nonlinear wave interactions, wave turbulence and rogue waves [HyIV-Marintek-02] Ocean Basin Laboratory, Marintek Author: Jamie Luxmoore, Lancaster University, UK

2 Status form Document information Project acronym HyIV-Marintek-02 Provider Marintek Facility Ocean Basin Laboratory Title Experimental investigation of nonlinear wave interactions, wave turbulence and rogue waves 1 st user group contact (name/ ) Suzana Ilic, s.ilic@lancaster.ac.uk 2 nd user group contact (name/ ) Jamie Luxmoore, j.luxmoore@lancaster.ac.uk 1 st provider contact (name/ ) Ivar Nygaard, Ivar.Nygaard@marintek.sintef.no 2 nd provider contact (name/ ) Csaba Pâkozdi, Csaba.Pakozdi@marintek.sintef.no Start date experiment (dd-mm-yyyy) End date experiment (dd-mm-yyyy) Document history Date Status Author Reviewer Approver Draft J. Luxmoore Jens Kirkegaard Document objective This document describes the data that was obtained during this project and how it was stored, so that others than the people immediately involved may use the data for their research. Acknowledgement The work described in this publication was supported by the European Community s Seventh Framework Programme through the grant to the budget of the Integrating Activity HYDRALAB IV, Contract no Disclaimer This document reflects only the authors views and not those of the European Community. This work may rely on data from sources external to the HYDRALAB IV project Consortium. Members of the Consortium do not accept liability for loss or damage suffered by any third party as a result of errors or inaccuracies in such data. The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and neither the European Community nor any member of the HYDRALAB IV Consortium is liable for any use that may be made of the information.

3 Contents 1 Objectives Experimental setup General description Definition of the coordinate system Relevant fixed parameters Instrumentation and data acquisition Instruments Definition of time origin and instrument synchronization Measured parameters Experimental procedure and test programme Remarks...9

4 1 Objectives The aims of the tests reported in this document are to isolate the mechanisms that lead to the creation of extreme waves and in particular rogue waves on the water surface. The tests have also been designed to allow study the wave dynamics and statistical properties of extreme and rogue waves under conditions close to those found in an open sea. The mechanisms identified will be compared to theoretical wave turbulence models. Comparison of the test results with numerical model simulations based on wave turbulence theory will provide important information on the mechanisms responsible for freak wave formation and will constitute a basis for further development of the theory of this phenomenon. 2 Experimental setup 2.1 General description The Ocean Basin was filled with water to a depth of 3 m and instrumented with wave gauges. Multidirectional and crossing waves were produced by the multiflap wavemaker. The large wavemaker was not used in these tests. A wave absorbing system is in place at the side opposite to both wavemakers. A general schematic of the wave basin is shown in figure 2.1. Figure 2.1: General view of the wave gauges and wavemakers in the Ocean Basin 2.2 Definition of the coordinate system The origin is at the centre of the tank, 34.6 m from the large wavemaker (BM2) and 24.8 m from the multiflap wavemaker (BM3). Positive x is across the tank towards the large wavemaker; positive y is down the tank away from the multiflap wavemaker; as shown in

5 figure 2.1. The origin in the z axis is at the still water level, with positive z being up (the floor of the tank is at z = -3 m). 2.3 Relevant fixed parameters The water depth was kept constant at 3 m throughout the tests. The position of the wave gauges was also kept constant. 3 Instrumentation and data acquisition 3.1 Instruments The Ocean Basin was instrumented with 24 resistance type wire wave gauges. The wave gauges are set to sample at 200 Hz and a Butterworth 4 th order low pass filter is applied with a cut off frequency of 20 Hz. Video records were also made of the tests from the control room looking down across the tank (from the same angle as the photograph on page 1). The position of the gauges relative to the origin is shown in table 3.1. Table 3.1: Wave gauge location x y Number Name m m 1 01_ _ _ _ _ _ _ _ _ _ _CENTER _ _ _ _ _ _ _

6 3.2 Definition of time origin and instrument synchronization The measurements start when the wavemaker starts generating waves and continue for about 3 minutes after the last wave is generated. The tank was allowed to settle between tests for 20 minutes. All measurements are taken at 200 Hz and all are synchronized to the time data recorded. The direction of the waves is recorded as an angle with 90 degrees being parallel to the positive y axis (down the tank away from the multiflap wavemaker). 3.3 Measured parameters Surface elevation is recorded at each of the 24 wave gauges. The time from the start of wave generation is also recorded. The position of one of the flaps of the multiflap wavemaker is also recorded. A video record of all tests was also taken to estimate wave breaking. 4 Experimental procedure and test programme All of the experiments make use of the multiflap wavemaker only (the large wavemaker was not used). The multiflap wavemaker has 144 flaps of just under 0.5 m width. The last 9 paddles (at around x = 31.5 m to x = 35 m) were switched off throughout the tests to reduce the area affected by reflections off the large wavemaker. Six main sets of experiments were performed over two weeks. Test series 2000 uses irregular JONSWAP distributed waves with a significant wave height (Hs) of m throughout. For most cases, two different sea states are generated simultaneously, either running parallel to each other or crossing. The peak period (Tp), the mean direction (Dir.), directional spread and the value of gamma in the JONSWAP spectrum are varied, as described in table 4.1. Test series 3000 is similar, but with Hs = m as described in table 4.2. This test series was discontinued as the amount of wave breaking was considered too high. All of the irregular wave tests were run for 20 minutes (generally over 1000 waves, depending on frequency). Test series 4000, 5000 and 6000 use one or more sets of regular waves. Wave height (H), wave period (T) and wave direction (Dir.) are varied, as described in tables 4.3, 4.4 and 4.5. The regular wave tests were run for around 100 waves. Test series 7000 uses three different sets of white noise based waves as described in table 4.6.

7 Table 4.1: Test series 2000: Irregular JONSWAP Sea state Hs = Directional Date Hs Tp Gamma Dir. (deg) spread (dd.mm) 2100 IRR 0.058/ / /90 G6/ IRR 0.058/ / /90 G6/6 N200/ IRR 0.058/ / /90 G6/6 N90/ IRR 0.058/ / /90 G6/6 N50/ IRR 0.058/ / /90 G6/6 N24/ IRR 0.058/ / /90 G3/6 N200/ IRR 0.058/ / /90 G3/6 N90/ IRR 0.058/ / /90 G3/6 N50/ IRR 0.058/ / /90 G3/6 N24/ IRR 0.058/ / /85 G3/6 N50/ IRR 0.058/ / /80 G3/6 N50/ IRR 0.058/ / /75 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /110 G3/6 N200/ IRR 0.058/ / /110 G3/6 N90/ IRR 0.058/ / /110 G3/6 N50/ IRR 0.058/ / /110 G3/6 N24/ IRR 0.058/ / /110 G3/6 N50/ IRR 0.058/ / /110 G3/6 N840/ IRR 0.058/ / /115 G3/6 N50/ IRR 0.058/ / /90 G3/6 N50/ IRR 0.058/ / /90 G3/6 N50/ IRR 0.058/ / /90 G3/6 N50/ IRR 0.058/ / /85 G3/6 N50/ IRR 0.058/ / /85 G3/6 N50/ IRR 0.058/ / /85 G3/6 N50/ IRR 0.058/ / /80 G3/6 N50/ IRR 0.058/ / /80 G3/6 N50/ IRR 0.058/ / /80 G3/6 N50/ IRR 0.058/ / /75 G3/6 N50/ IRR 0.058/ / /75 G3/6 N50/ IRR 0.058/ / /75 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /70 G3/6 N50/ IRR 0.058/ / /90 G6/ IRR 0.058/ / /90 G6/ IRR G IRR G3 N IRR G3 N IRR G3 N IRR G3 N IRR 0.058/ / /110 G3/6 N200/ IRR 0.058/ / /110 G3/6 N200/ IRR 0.058/ / /110 G3/6 N200/ IRR 0.058/ / /110 G3/- N50/ IRR 0.058/ / /110 G3/6 N200/ IRR 0.058/ / /110 G3/6 N840/ IRR 0.058/ / /110 G3/6 N840/ IRR 0.058/ / /110 G3/6 N840/

8 Table 4.2: Test series 3000: Irregular JONSWAP Sea state Hs = Directional Date Hs Tp Gamma Dir. (deg) spread (dd.mm) 3100 IRR 0.068/ / /90 G6/ IRR 0.068/ / /90 G6/6 N200/ IRR 0.068/ / /90 G6/6 N90/ IRR 0.068/ / /90 G6/6 N50/ IRR 0.068/ / /90 G6/6 N24/ IRR 0.068/ / /90 G3/6 N200/ IRR 0.068/ / /90 G3/6 N90/ IRR 0.068/ / /110 G3/6 N200/ Table 4.3: Test series 4000: Trichromatic Waves Date H T Dir. (deg) (dd.mm) 4100 REG 0.2/0.12/ /2.5/ /90/ REG 0.2/0.12/ /2.5/ /90/ Table 4.4: Test series 5000: Bichromatic Waves Date H T Dir. (deg) (dd.mm) 5100 REG 0.068/ /1 95/ REG 0.068/ /1 100/ REG 0.068/ /1 105/ REG 0.068/ /1 110/ REG 0.068/ / / REG 0.068/ / / REG 0.2/ /2.5 90/ REG 0.2/ /2.5 90/ REG 0.068/ / / REG 0.068/ / / REG 0.068/ / / REG 0.068/ / / REG 0.068/ / / REG 0.068/ / / REG 0.068/ / /

9 Table 4.5: Test series 6000: Monochromatic waves Date H T Dir. (deg) (dd.mm) 6500 REG REG REG REG REG REG REG REG REG REG REG REG REG REG REG REG REG REG REG Table 4.6: Test series 7000: Tailored Time Series Date (dd.mm) 7110 REG noise_ REG noise_ REG noise_1_ Remarks No remarks are necessary.