As it can be seen ,body Y and flow Y graph of Hereflow Optical sensor is different from each other. In other words, it is not following each other. Can you please suggest how to rectify this problem. Please note we are disabled the compass and also not using GPS.
Please note that you should not disable the compass.
Is there any way to calibrate the sensor or rectify this problem?
Yes, you can and must calibrate both the compass and the OF sensor. And use both.
As always, both calibrations are included in the ArduPilot methodic configurator software. Use it.