3-DIMENSIONAL PATTERNS IN A TRANSIENT, STRATIFIED INTRUSION FLOW

The cross-stream dimension of a horizontal, thermally stratified intru sion flow, that travels underneath an insulating wall into a heavier, isothermal fluid, is investigated experimentally. The observed develop ment of a regular temperature variation along that third dimension is linked to a Rayleigh-Benard-like instability, which is caused by the f act that the upper part of the intrusion flow is effectively heated fr om below through internal heat advection. These results can be underst ood by Linear stability calculations and contradict the assumption of all previous investigations that the flow is essentially two dimension al.