<div>Hello Brian,</div><div> </div><div>There are others who know more, but what I remember about Bead and Terracette is that the pool of Terracette rises and falls every few minutes and generally each rise is a bit higher than the last one. Just about when it looks like Terracette may overflow, Bead will usually erupt. This results in Terracette dropping far down, then the whole process happens again. </div> <div> </div><div>Stephen Eide<br><br></div><div class="gmail_quote">On Fri, Mar 16, 2012 at 12:00 PM, Davis, Brian L. <span dir="ltr"><<a href="mailto:brdavis@iusb.edu">brdavis@iusb.edu</a>></span> wrote:<br><blockquote style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid" class="gmail_quote"> Thank you for all the responses; you’ve given me a lot to think about. But I fear I was not as specific in my first request, so let me explain a bit more.<br> <br> Fluid in a U-tube will oscillate if displaced (the water sloshes back and forth between the two upright arms of the U-tube). The frequency depends on the depth and length of the U-tube. So for instance two pools connected at depth could exhibit this behavior (if disturbed), and you could get an idea of the depth and size of the plumbing system below them.<br> <br> I once set up a model where a reservoir with a large cross-section (a wide pool) is connected by a deep U-tube to a small vent in a basin on the other arm. I heated it with a heat tape, and found that while I couldn’t get a full eruption, the whole system oscillated with a very well-defined period, upwelling smoothly out of the vent, and then reversing and shifting to the reservoir. There was no indication that there was any steam phase in this model (while the water got hot, no steam was released, and given the low heat input and small conduit I used at the time it’s doubtful it ever reached boiling point). As a “Steamboat/Cistern” style model, it was a failure and I moved on.<br> <br> With Bead Geyser / “Terracette Spring”, I was wondering if they functioned in opposition (one rising while the other falls), or synchronous (both rising together, and receding together). Another suspicious pair to me is (Grotto’s) Indicator Spring, which from the description only ends up oscillating as the system heats up, and does so on a regular schedule. A thermally-excited U-tube is not a model I had thought of before, but I am now with respect to some of these issues (in addition to the more obvious case of one geyser erupting, thereby lowering hydrostatic pressure in one conduit and inducing flow from surrounding ones, as seems to happen in many examples).<br> <br> Such oscillations can certainly occur with eruptions – Turban / Grand would seem a classic example of this, and there are many others. But I’m actually thinking along the lines of non-erupting pairs with regular oscillations.<br> <br> As to the rest of the examples offered… all I can say is Thank You! Some of these I knew and have tried to study or model, but some of them I had not thought of and need to dig into still more. This list is a fantastic resource for me and I really appreciate the willingness to talk about and describe these things.<br> <div class="HOEnZb"><div class="h5"><br> --<br> Brian Davis<br> _______________________________________________<br> Geysers mailing list<br> <a href="mailto:Geysers@lists.wallawalla.edu">Geysers@lists.wallawalla.edu</a><br> <a href="https://lists.wallawalla.edu/mailman/listinfo/geysers" target="_blank">https://lists.wallawalla.edu/mailman/listinfo/geysers</a><br> </div></div></blockquote></div><br>