gaber

I have no problems understanding all what you claim and you are right. My question was: can you foresee any settings where the high discharge (500 l/s) siphoning can be triggered (no valves or any moving parts) by low constant inflow (3 l/s) with Volume 2 in your scetch of 1000 m3 ?

Good idea, but the diameters here are bit smaller (10-20 cm) than in Fintaine de Vaucluse; and iy is not a mystery anymore. Its genesis and action is now well understood. Thanks for the posts. We are dealing with conduits or solutionally enlarged fractures. Chambers in soluble rocks can be several milions cube meters large, so 1000 cube meters is no problem. So, we do not need low pervious and high pervious rocks (it wouldn't work in such a riforous manner in any case). The problem, however, still remains. For the siphon to act, you need to fill the outflowing tube completely (or almost completely). The tube in your picture will act as a simple overflow with free surface flow (a "weir") if your inflow is not large enlogh to fill it. If you look the funny fountain video, the recharge is colose to the siphoning discharge. In that case I see no problem. Try it with very small recharge, will it work than ?

Exactly that is the problem: how to trigger "high discharge" siphoning with constant low discharge inflow into the reservoir, without any man made mechanisms. I was having air locks or some other role of air in mind, but still, this is a rather general idea. I have put some conceptual picture on https://www.dropbox.com/sh/qp12m1d313sqeq8/fZ_IYcXrWg. The question is how to fill the tube (or get the air out) to start siphoning. Any hint, link to literature is most wellcome. Thanks for thinking my problem.

1. Yes, latest this morning . 2. No. Empirical facts: Even with relatively high steady inflow there is no intermittent action.

I am looking for an idea related to a siphon mechanisms that has been puzzling me for a while. I am doing a small research on a natural (karst) spring, that has a cyclic (intermitent) behaviour. The low-flow discharge of the spring is in the range of few litres per second, during outbursts it rises up to 500 l/s. The total volume discharged during the outburst is about 1000 m^3. The frequency of outbursts ranges between few hours and few weeks, depending on the amount of precipitation which determines the recharge to the system. Note, that we do not know the geometry of the system; we have an access to the spring pool and we expect a natural reservoir which empties by siphon action through the conduit feeding the spring during the outburst. The usual interpretation of such spring is a siphon mechanism, which I agree. However, my problem is a high contrast between the low flow and the high flow. Imagine a simple system with a reservoir with inflow of few L/s, emptying through a looping conduit/pipe to a lower position. How can a siphon effect be triggered in such system with such low inflow, if the same conduit drains 500 L/s during the outburst. Am I getting something wrong to see the problem here ? So, I am looking for possible geometries and mechanisms which could occur in nature (no valves, switches, constant geometry…), that enables cyclic siphoning of a system with maximal discharge - recharge ratio in the range of two orders of magnitude. I could post this to earth science section, but I consider this a rather mechanical problem.