FRONT DYNAMICS IN MISCIBLE DISPLACEMENT FLOW IN A CURVED PIPE

Miscible displacement flow in a curved pipe with two fluids of equal viscosity and in the regime of low Atwood number is studied experimentally at different Reynolds and Atwood numbers. By using a curved pipe the effect of curvature on miscible displacement flow is studied. Curvature may be present in many displacement flow processes in nature or industry which underlines the necessity of studying its effect on displacement flow. As the flow is controlled by gravity as the main driving force, only low to moderate Reynolds numbers are considered and Atwood number is varied by adding NaCl salt to fresh water. This makes it possible to create different values of Atwood numbers which can be varied continuously. The position of the leading front is carefully recorded using a digital camera and is used as a measure of displacement efficiency. It is observed that the ratio of the front velocity to the mean velocity approaches a certain value as Reynolds number increases. The effect of Atwood number on flow dynamics is also studied based on experimental results and is interpreted following the conventions employed in some of the previous researches.