Submerged Orifice with No Change in Head?

Hi Melanie,

I am having trouble understanding your question. Do you mean that the submerged orifice is between two separate tanks; and that both tank levels are the same?

Please describe carefully the situation. Do NOT be afraid to give too much information! The more detail, the better chance you have of getting a decent answer.

Mike

It's a matter of definition, a 'head' is just a pressure difference. Thus any pressure difference will do, it could be generated by a pump, or the rotation of the earth or the pull of the moon. Once a flow is established the water will of course have considerable momentum, and may appear to be flowing despite little or no head.
How much 'head' is there in the lower reaches of the Mississippi?

This sounds almost like a riddle,

if the apparent initial "head" is equal, then the flow could be caused by a difference in density of the fluids on both sides of the orifice, which would be a temporary condition until equalizing, depending upon the volumes this may take considerable time. The density is of course affected by temperature, atmospheric pressure, bubbles thru one of the liquids, ...

Heavy water on one side.

Generally, you will not have flow through such an orifice or pipe unless you provided another source of pressure drop across said orifice or pipe.

Is this a homework question?

Water moves through an orifice when there is a energy grade difference. Three components make up the energy grade for the water on each side of the orifice, Pressure, Elevation, Velocity. A difference across the orifice in any of these could allow water to move through the orifice. Additionally other factors such as diffusion allows water the move across an orifice (in both directions) as the two fuilds equilibrate differences in the properties of each fluid (i.e. chemical or thermal gradients).

The most likely answer is temperature difference.