The flow of Newtonian fluid (eg. water) in the test channel with an obstruction at the entrance placed in a wider channel was seen to be stagnant, forward or reverse depending on the position of the obstruction. This interesting flow phenomenon has potential benefit and can be employed in the control of energy and various flows in process engineering. This study was extended to non-Newtonian fluid for further investigation using flat plate as an obstruction. A low concentration polyacrylamide fluid solution (0.018%) showing non-Newtonian fluid behavior was used in this investigation. The parameters that affect the flow inside and around the test channel were the gap (g) between the obstruction geometry and the test channel, the Reynolds number and the length of the test channel. The maximum reverse flow inside the test channel observed was 20%-25% of the outside test channel velocity at g/w (gap to width) ratio of 1 for Reynolds number of 1000 to 3500. The results of the influence of the test channel length and the Reynolds number on the velocity ration (Vi/Vo: inside velocity/outside velocity in the test channel) is also presented and discussed.