Ultrasonic fluid flow assist?

We have a substantial number of large non-pressure vessels with conical bottoms holding large quantities of high-viscosity fluids. Over time, we have developed new products of higher and higher viscosity. Now we find that the product is slow to start flowing, may not flow at all from a partially full tank, and leaves too much product in the vessel.

We're looking for ways to help the product flow. Air pressure on the surface is not an options, neither is heating the product due to degradation of some components. We're exploring technical alternatives.

Does anyone have any feedback about possibly using ultrasonic devices in the cone of the vessel to help break down the fluid yield point and viscosity at the bottom of the vessel?

Thanks,

Andrew