Changes between Version 45 and Version 46 of WikiStart
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- Sep 15, 2017, 2:13:28 PM (7 years ago)
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WikiStart
v45 v46 214 214 The reflection is now ok and we can start our experiments! 215 215 216 '''Test experiment EXP01''' 217 216 === '''Test experiment EXP01''' === 218 217 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. 219 218 … … 226 225 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.''' 227 226 228 '''Experiment EXP02''' 229 227 === '''Experiment EXP02''' === 230 228 We repeated the HS with a reduced time to 200 ms between the photos and and exposure time of 30ms'''. We realized afterwards that the cameras only took every second photo, so with a time interval of 400ms! ''' 231 229 … … 234 232 The cameras are fixed now and taking every photo and the particles are spread out in the ambient water. 235 233 236 '''Experiment EXP03''' 237 234 === '''Experiment EXP03''' === 238 235 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! 239 236 240 237 The current reached the first corner after about 1 minute, and the trough corner after about 3 minutes. 241 238 242 '''Experiment EXP04''' 243 239 === '''Experiment EXP04''' === 244 240 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). 245 241 … … 248 244 Observations: The bubble at the source disappeared due to the lower flow rate. The current follows along the slope and turns left at the 2nd curvature into the trough. After the 15 min after the flow was turned on, the flow bifurcates at the continental coast and at the trough and fills up the trough. The return flow does not follow along the upstream slope of the trough, but occurs in the middle of the trough. The main current along the slope is getting wider with time. [[BR]]'''''''''' 249 245 250 '''Experiment EXP05''' 251 246 === '''Experiment EXP05''' === 252 247 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). 253 248 … … 260 255 The current was at the first corner about 1 minute after the valve was opened. 261 256 262 '''Experiment EXP06''' 263 257 === '''Experiment EXP06''' === 264 258 The squared cornes were inserted - the land corner was fastened with tape and the submerged corner with a screw.. 265 259 … … 268 262 The flow separated at the first corner and turned at the second corner. 269 263 270 The vertical scann was started 15 min after the valve was opened. 271 272 '''Experiment EXP07''' 273 264 The vertical scann was started 15 min after the valve was opened.'''''' 265 266 === '''Experiment EXP07''' === 274 267 An eddy initially forms behind the first corner, but it then disappears. 275 268 … … 280 273 '''7.6 Thursday 14 September''' 281 274 282 '''Experiment EXP08''''''' 283 275 === '''Experiment EXP08''' === 284 276 The squared corners are still on, for the first 3 minutes of the horizontal slice the light in the entrance was turned on. 285 277 … … 292 284 This is to avoid shaking of laser. 293 285 294 '''Experiment EXP09''' 295 286 === '''Experiment EXP09''' === 296 287 The squared corners are removed and the flow rate is reduced. There were a lot of particles in the inflow in the beginning. 297 288 … … 300 291 The laser sheets were started 26 minutes after the valve was opened. 301 292 302 '''Experiment EXP10''' 303 293 === '''Experiment EXP10''' === 304 294 The flow rate is increased, there are again a lot of bubbles. 305 295 … … 310 300 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 311 301 312 '''Experiment EXP11''' 313 302 === '''Experiment EXP11''' === 314 303 The water level is increased by 10 centimeters to 68.5 cm. 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. 315 304 … … 337 326 Note: After Exp11 they realized that there was water in the laser, they had to go and move it up. 338 327 339 '''Experiment EXP12''' 340 328 === '''Experiment EXP12''' === 341 329 This experiment was the same as EXP11 with a water level of 68.5 cm but with the corner. The expected flowrate was 33 l/min and the measured flowrate was 34.6 l/min. 342 330 … … 344 332 345 333 == 7.7 Friday 15 September == 346 === Experiment 13 ===334 === Experiment EXP13 === 347 335 During night, we increased the rotation rate to get a rotation period of 30s! We kept the corners. 348 336 … … 359 347 Note: The source is leaking, which created bubbles and a little "waterfall" due the the water surface difference inside and outside the source. Thomas fixed it by putting a wooden block in front of the leakage. 360 348 361 '''Experiment 14''' 362 363 We increase the influx to a desired value of 80 l/min with still the higher water level and increased rotation rate. 364 365 Due to the high flux rate, we use an exposure time of 30 ms. 349 === '''Experiment EXP14''' === 350 We increase the influx to a desired value of 80 l/min with still the higher water level and increased rotation rate. 351 352 Due to the high flux rate, we use an exposure time of 30 ms. 366 353 367 354 Notes: 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.