Hydraulics Videos

Water Hammer Explained

Water Hammer Wave Reflection and Valve Closure Time

Waterfall Flow & Air Blockages in Pipes Explained

Youtube video- Hydraulic Modelling with Modelica & SimulationX

Youtube video- Hydraulic Modelling and design using SimulationX

YouTube video - Hydraulic modelling using wanda

Youtube video- Surge analysis of pump trip

Comments and Questions

  • Sean Bell

    Hi Mike – just watched your video on waterfall and airlocks within piped systems (loved it) and have a couple of queries I would greatly appreciate some more insight on. Firstly the H2 loss – does the gravitation gain (generated on the negative flow gradient) contribute to reducing the H2 loss? Or could this create higher velocities with the increased pressure aiding in H2 loss? If not – pending on the specifics of the systems (pipe dia, fluid viscosity, velocities, densities) would it be possible to design a potable water system that the gravitation gain on the negative flow gradients be greater than the calculated H2 loss? Secondly towards the end of the video you touched on large infrastructure mains where you typically see larger dia’s and pressures with lower velocities – would you suggest a higher velocity and pressure to mitigate a) vaporization within water systems pending temperature ranges and b) to help push the gas along the highest point? All the best and look forward to watching the other videos

  • Once you have a bubble that is stuck at a high point you always get head loss. Its exactly like the flow of water over a waterfall or weir. The potential head after the weir or waterfall is always reduced by the amount of drop.

    Using higher velocity to push the gas along is often counter productive because the friction loss is proportional to the velocity squared. So you may reduce the waterfall flow losses but increase the friction flow losses more. So there is no easy answer to this question, it depends on the system.

  • Hemaka Lakmal

    In a system where you’d get surges due to pump trips, is it necessary to position the surge tanks as closer as possible to the pumps? It would be really helpful if you could do some videos on surges that develop specially after scenarios like pump trips, cases where downstream surges occur. Thank you

  • Generally it is best to have the surge tanks as close as possible to the pumps. Typically on a water system the surge vessels would be within about 25m of the pumps, but there are no fixed rules for this and a full computer simulation surge analysis would be required to determine if the proposed location of the surge vessel was acceptable.

  • Wade

    Mike – I watched video on airlocks and waterfall flow (THANKS) and have an application nearly identical to this. The top is vented at the same location as your sketch and releases only water, but I hear intermittent collapsing sounds in the downward section of pipe.

    At what point does the water velocity carry away the air? Is 10ft/sec sufficient? (h2 is 18ft and pipe size is 72inch diameter). Is the head loss “h2” eliminated if there is no air at the vent?

    I have increased restriction (higher pump discharge pressure) and reduced flow since this modification was installed and looking to eliminate increased head loss.

    Thanks for any help.