# Changes between Version 42 and Version 43 of WikiStart

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Timestamp:
Sep 15, 2017, 1:26:24 PM (4 years ago)
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 v42 '''Test experiment EXP01''' We conducted experiments with a long HS from the beginning after turning on the influx (EXP_01). The influx was 41 L/min with a diaphragma of 12.6 mm diameter. The influx water had a density of 998.2 and was enriched with particles of size 30mikrom. The laser sheet was at 11cm over the trough, 4 cm over the shelf, so at 54 cm when the laser setting was at 650. We decreased it to 640 to have the laser sheet at 55 cm. Water Level (supervision - this changes witha few mm when People come enter/leave the rotating Office) was at 58.4 cm. The exposure time of the cameras was at 50ms  and the time interval 500 ms. We conducted experiments with a long HS from the beginning after turning on the influx (EXP_01). The influx was 41 L/min with a diaphragma of 12.6 mm diameter. The influx water had a density of 998.2 and was enriched with particles of size 30mikrom. The laser sheet was at 11cm over the trough, 4 cm over the shelf, so at 54 cm when the laser setting was at 650. We decreased it to 640 to have the laser sheet at 55 cm. Water Level (supervision - this changes witha few mm when People come enter/leave the rotating Office) was at 58.4 cm. The exposure time of the cameras was at 50ms and the time interval 500 ms. We switched to the VS at 14:58 (EXP01_VERT). terwards we started the Scan at 15:15 (EXP01_SCAN) with the same camera settings as for the HS. The slices were at the heights of 55 cm to 30 cm in 5 cm steps. We took 4 images at each height with a time interval of 500 ms. Observations: On the horizontal scans we can clearly see turbulent/vertical motion along the coast. They turn left at the curvature and follow along the topography to the wall. Some particles turn right above the trough/ shelf and flow out to the slope again. Observations: On the horizontal scans we can clearly see turbulent/vertical motion along the coast. They turn left at the curvature and follow along the topography to the wall. Some particles turn right above the trough/ shelf and flow out to the slope again. Data check: We checked these first results with the PIV and decided to decrease the exposure time to get sharper images of the particles. With PCO2, the flow around the curvature can be captured with the PIV, but on PCO1 the PIV is not very good, because the flow is more turbulent and more 3 dimensional. We decide to decrease the time between the photos. '''Later we realized that the cameras only took every second photo, so with a time interval of 1000ms - > useless PIV.''' The setup is still the same as for the previous experiments with 200ms time difference between the photos (this time working!) and particles in the ambient water. This time, we measured the flow rater AFTER the experiment and it was $Q = 50 l/min$ (measurements repeated twice), as expected. There are still bubbles coming out of the source! The current reached the first corner after about 1 minute, and  the trough corner after about 3 minutes. The current reached the first corner after about 1 minute, and  the trough corner after about 3 minutes. '''Experiment EXP04''' We started a new experiment at !10:31 with a reduced flow rate of about $Q = 20 l/min$ (diaphrama diameter of 6.8 mm). The first HS is run for 15 min n(!10:31- !10:46). The flow field was still evolving so we extended the five more minutes of hs (!10:51-10:56  this data are stored in EXP04_B) before we started the scan ( !10:59). We started a new experiment at !10:31 with a reduced flow rate of about $Q = 20 l/min$ (diaphrama diameter of 6.8 mm). The first HS is run for 15 min n(!10:31- !10:46). The flow field was still evolving so we extended the five more minutes of hs (!10:51-10:56  this data are stored in EXP04_B) before we started the scan ( !10:59). Note: During the scan, the laser is shaking too much! This needs to be changed. '''Experiment EXP05''' The vertical velocity of the laser was decreased and the timestep between the first and the second image at each level increased to 1s (first image will be discarded). The vertical velocity of the laser was decreased and the timestep between the first and the second image at each level increased to 1s (first image will be discarded). The tank from where the inflow is pumped was mistakenly filled with too much Cold water (T=19.2C) - i.e. about 4 c colder than the water in the tank. There where a lot of Bubbles coming out from the Source - and we observed large (10 cm) airbubbles travelling Down the hose during the Experiment. All the water turned at the first water, onto the shelf. There where a lot of Bubbles coming out from the Source - and we observed large (10 cm) airbubbles travelling Down the hose during the Experiment. All the water turned at the first water, onto the shelf. The current was at the first corner about 1 minute after the valve was opened. The squared cornes were inserted - the land corner was fastened with tape and the submerged corner with a screw.. To reduce to amount of Bubbles coming out from the Source we added a thin sheet of foam behind the honey comb. In addition, the joints of the tube where the diaphragm is inserted was greased. This appeared to help - the amound of Bubbles was greatly reduced and no Bubbles was seen travelling Down the hose. To reduce to amount of Bubbles coming out from the Source we added a thin sheet of foam behind the honey comb. In addition, the joints of the tube where the diaphragm is inserted was greased. This appeared to help - the amound of Bubbles was greatly reduced and no Bubbles was seen travelling Down the hose. The flow separated at the first corner and turned at the second corner. The vertical scann was started 15 min after the valve was opened. '''Experiment EXP07''' '''Experiment EXP07''' An eddy initially forms behind the first corner, but it then disappears. '''7.6 Thursday 14 September''' '''Experiment EXP08'' The squared corners are still on, for the first 3 minutes of the horizontal slice the light in the entrance was turned on. The flow turned left at the second corner following the slope in the depression keeping a "tight" shape on the topography. '''Experiment EXP08''''''' The squared corners are still on, for the first 3 minutes of the horizontal slice the light in the entrance was turned on. The flow turned left at the second corner following the slope in the depression keeping a "tight" shape on the topography. After a while, a straight flow established, following the slope. The circulation is very slow compared to yesterday. The flow rate is increased, there are again a lot of bubbles. The beginning of the "jet" took less than 1minute to reach the 1st corner. After the reaching the first corner a major part of the flow followed the boundary and circulated on the shelf. After the reaching the first corner a major part of the flow followed the boundary and circulated on the shelf. A smaller part continued to the corner of the slope and the depression (after 3minutes) and entered the depression, circulated along the topography and escaped by the western side of the depression '''Experiment EXP11''' The water level is increased of 10 centimeters compared to the previous experiment. There are no more bubbles The flow crossed the shelfbreak between the 1st and the 2nd corner. After the flow is established it follows along the rough topography and returns along the continental coast. The water level is increased of 10 centimeters compared to the previous experiment. With the higher water level, we need to calculate new flow rates with the ration of the outflow area before and after the higher water level. Now, we are aiming to a flow rate of 33 l/min, which corresponds to the 20 l/min for the lower water level. ||Q (low water level)||Q (high water level)|| ||10|||| ||20||33|| ||35|||| ||50|||| ||80|||| Observations: There are no more bubbles. The flow crossed the shelfbreak between the 1st and the 2nd corner. After the flow is established it follows along the rough topography and returns along the continental coast. There was no straight flow along the slope. There were very few particles in the end of the horinzontal slice. On the vertical slice the flow does not look barotropic. After Exp11 they realized that there was water in the laser, they had to go and move it up. After that the water level was measured : 72.7cm at the edge and 68.5cm over the topography. ''6 - Table of Experiments: '' - will be updated from Excel sheet! There were very few particles in the end of the horizontal slice. On the vertical slice the flow does not look barotropic. Note: In the previous experiment, the measured flow rate was always higher than the expected one with their diaphragme - flowrate curve. We plotted the diaphrame vs. flowrate again with the values from our experiments. For the flowrate of Q = 33 l/min, we therefore used a diaphragme with  diameter of 10 mm, instead of 8.6 mm (which it was for the 20 l/min flux  before).[[BR]]We measured the flux 4 times during this experiment. It gave:[[BR]]- 32.4 l/min[[BR]]- 34.5 l/min[[BR]]- 33.3 l/min[[BR]]- 34.9 l/min Note: After Exp11 they realized that there was water in the laser, they had to go and move it up. New measured water level: 72.7cm at the edge and 68.5cm over the topography. '''Experiment EXP12''' This experiment was still without the corner and a water level of 68,5 cm. 7.7 Friday ''6 - Table of Experiments: '' * will be updated from Excel sheet! ||'''''Exp No.'''''||'''''Name'''''||'''''Valve opened'''''||'''''$H_{water}$'''''||'''''$T_{rot}$'''''||'''''$Q$'''''||'''''$R_{curvature}$'''''||'''''$\Delta \rho$'''''||'''''Diaphragme'''''||''''' Flowrate estimated'''''||''''' Type of photo'''''||'''''Height of HS'''''||'''''Heights of Scan and #'''''||'''''Time photo'''''||''''' Dye'''''||'''''Comments'''''||''' Notes'''||