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The "straw" is fixed to the main support spider, the cable, which could also be a thin rod like a bicycle wheel spoke, is affixed to the sample holder (with a screw thread?) and the slider being tested sits on the sample holder. So the slider and sample holder can move up and down together and if the cable is a thin rod then a rubber seal could be placed at the bottom of the "straw" to keep water out of the tube, although it could also contain water that did not move into or out of the bore of the "straw". Main problem is the bore of the vertical column, turbulent flow will start at a certain flow rate for that bore size, so you would need to know the Reynolds number for the tubing used for the column.Thanks! Seems to be a serious measuring device. Could water enter the hollow plastic "straw"? What is the role of sample holder if slider is bind to measuring cable? Is the "straw" movable up-down or fixed?
Hi Guys i thought this might be useful, the riffe slider is the best for hydrodynamics in my opinion. Also it will hold a good fish.
Maybe a digital kitchen scale could be used with a set-up like this.View attachment 38483
Another idea for testing sliders perormance:
I think the diameter of the test tank must be very large to prevent turbulence inside the water column itself which would otherwise swamp the effects of the slider changes on the measurements. Another approach may be to drag the slider through the water on the end of a fishing line, like a lure, but how to measure the very small variation in the drag, the slider being mounted on a section of "shaft" (or a slim cylindrical body)?