Changes between Version 54 and Version 55 of WikiStart


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Timestamp:
Sep 20, 2017, 10:58:52 AM (3 years ago)
Author:
steiger5na
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    v54 v55  
    372372Notes: The water level increased constantly. After this experiment, we had to adjust the sink to let out more water. It takes some time, so we had to wait until the water level was good again.
    373373
    374 Water level on the screen : 63.4cm. The desired flux rqte was 80L/min, we used the 16mm diaphragm and measured a rate of 94.7L/min.
     374Water level on the screen : 63.4cm. The desired flux rate was 80L/min, we used the 16mm diaphragm and measured a rate of 94.7L/min.
    375375
    376376Observations : The flow took 20s to reach the first corner, nothing crosses the shelf, a circulation is created on the shelf by water turning on the 1st or 2nd corner.
     
    387387After that a third smaller branch started to follow the slope.
    388388
    389 Note : After this experiment, inertial oscillations appeard and the water started to move so we had to wait until further experiments.
     389Note : After this experiment, inertial oscillations appeared and the water started to move so we had to wait until further experiments.
    390390
    391391=== Experiment EXP16 ===
     
    394394The desired flow was 35L/min, with the diaphragm of 10mm we measured 36L/min.
    395395
    396 Observations : At the first corner a larg part of the flow turned left and went on the shelf, circulating in a larger vein than the previous experiment.
    397 
    398 Some water reaches the 2nd corner spliting in a major part entering the depression and a smaller and slower part flowing along the slope.
    399 
    400 There was no recirculation inside the depression, all the flow was evactued at the end of the depression bypassing the "land".
     396Observations : At the first corner a large part of the flow turned left and went on the shelf, circulating in a larger vein than the previous experiment.
     397
     398Some water reaches the 2nd corner splitting in a major part entering the depression and a smaller and slower part flowing along the slope.
     399
     400There was no recirculation inside the depression, all the flow was evacuated at the end of the depression bypassing the "land".
    401401
    402402=== Experiment EXP17 ===
     
    407407Observations : At the 1st corner the flow continued straight ahead. At the 2nd corner the flow split in 2 branches of equal size, one following the slope and on entering the depression.
    408408
    409 There was a very clear a very clear and narrow jet following the bathymetry inside the depression, with a lot of meanders on its sides.
     409There was a very clear and narrow jet following the bathymetry inside the depression, with a lot of meanders on its sides.
    410410
    411411After a while a branch detached from the slope current at the western corner of the depression entered the depression and recirculated joining the eastern side of the depression (drawing on the experiment paper).
     
    413413We wanted to keep the same setup and to increase the flow rate to 80L/min in order to have consistency but unfortunately we were running out of time.
    414414
     415==  ==
    415416== 7.8 Monday 18 September ==
    416417The whole day was used to build the extension of the topography to move the source 2m further back. The source sits now at the same position relative to the topography, only 2m further back. The cameras stayed at the same positions. We used this day to process data and to learn more about UVMAT.
     
    418419== 7.9. Tuesday 19 September ==
    419420=== Experiment EXP18 ===
    420 Today, first the source had to be attached and the water filled up. Then the particles had to be spread out in the water again. So the experiment didn't start before 11:30. [[BR]]At least, the source was now moved 2m further back and the foam of the source was improved to avoid bubbles leaving the source, which also worked with this flow rate. 
    421 
    422 Because the source was mainly too close for the high flow rates, we will only do experiments with flow rates higher than 50 and with a rotation rate of 50. We started with Q = 50l/min and no corner. 
     421Today, first the source had to be attached and the water filled up. Then the particles had to be spread out in the water again. So the experiment didn't start before 11:30. [[BR]]At least, the source was now moved 2m further back and the foam of the source was improved to avoid bubbles leaving the source, which also worked with this flow rate.
     422
     423Because the source was mainly too close for the high flow rates, we will only do experiments with flow rates higher than 50 and with a rotation rate of 50. We started with Q = 50l/min and no corner.
    423424
    424425Observations: The flow was much more established, when it reached the view of PCO1. Regular waves occurred along the slope until it reached the first corner. Almost the whole current turned south into the trough.
    425426
    426 Notes: The images for HS were accidently only taken for 7min, but restarted again for 7 min (EXP18_B). 
    427 
    428 == Experiment EXP19 ==
    429 We used the same setup at EXP18, just with a flow rate of Q=80l/min. Note that we still used the diaphragme of the original diameter-flow rate curve, which gives an actual flow rate of >90 l/min. We do that to be consistent.
     427Notes: The images for HS were accidently only taken for 7min, but restarted again for 7 min (EXP18_B).
     428
     429=== Experiment EXP19 ===
     430We used the same setup at EXP18, just with a flow rate of Q=80l/min. Note that we still used the diaphragme of the original diameter-flow rate curve, which gives an actual flow rate of >90 l/min. We do that to be consistent with previous experiments.
     431
     432From the PIV of previous experiments with a flow rate of 80, we have decided to decrease the dt from 100 to 50ms and also the exposure time from 30 to 20ms, because the correlations were not very high. However, the dt = 50 ms did not work during this experiment, so that in fact it was dt = 100ms, because only every second image was taken.
     433
     434During this experiment, the honeycomb fell out of the source after the HS. We did therefore no vertical scan.
     435
     436Note: This experiment had too many errors that we had to redo it!
     437
     438=== Experiment EXP20 ===
     439We redid experiment 19 and this time everything worked. dt is now 50ms and the exposure time 20ms. We had no corner. The measured flow rate was 93.5 l/min.
     440
     441Observations: Most of the current is entering the trough and a small part passes the trough, following the slope.
     442
     443=== Experiment EXP21 ===
     444For this experiment, we wanted to increase the flow rate to Q = 110 l/min, with a diaphragme of 17 mm. The measured flow rate was 120 l/min. The experiment was again without corner and dt = 50 ms, E = 20 ms.
     445
     446Observation: The whole current went into the trough.
     447
     448=== Experiment EXP22 ===
     449This experiment had the same setup as EXP21 but with the corner. The measured flow rate this time was only 100 l/min.
     450
     451Note: The flow rate is difficult to measure for high values, as the time interval is shorter and therefore produces a larger error. However, in the end we can plot a diameter - flow rate curve fitted with all the values from our experiment. The diaphragme should determine the flow rate quite clearly and with the fitted curve, we can get the actual flow rate.
     452
     453Observations: Most of the current went into the trough, only a small part passed by. There were many particles in the beginning of the experiment.
     454
     455== 7.10 Wednesday 20 September ==
     456=== Experiment EXP23 ===
     457After swirling up the particles in the tank, we started early at 08:13 with the first experiment. It is the same experiment as EXP22 with a flow rate of Q=80l/min. The calculated flow rate is 94 l/min, which is very close to the previous flow rate (100l/min).
     458
     459Observation: The flow was similar to the previous experiment, with the main current entering the trough. A large rotation occurred on the shelf.
    430460
    431461  '''' ''6 - Table of Experiments: '''''