Abstract: A fluid mechanical arrangement of a bluff body flowmeter in a pipe line is disclosed with a thermal sensor arrangement for sensing flow signals in that pipe and with a method and circuit for processing the sensed signals to subtract low frequency fluid noise signal that accompany sensed signal and extracting sensed signals related to the fluid flow rate through the pipe. Signal processing is achieved through a circuit comprising an inverting amplifier, peak detector, summing amplifier and trigger amplifier. The detector senses positive and negative peaks of the thermal sensed flow signals and produces signals the frequency of which corresponds to the flow rate of fluid through the pipe. The detector also generates negative and positive peak indicating signals and stores them in combination with an output image of the thermistor sensed fluid flow signal. The inverting amplifier inverts the thermal sensed signal for driving the peak detector.