What is the COSP flow model in a Doppler radar flowmeter?

The COSP flow model is the composite calculation model used by the HZ-KSLF multi-band Doppler radar flowmeter to convert surface velocity into cross-sectional mean velocity. Radar measures the surface velocity at one point on the water surface, while flow calculation requires the mean velocity over the whole wetted cross-section. The conversion between the two varies with channel shape and water level, which is the dominant source of error in non-contact gauging.

The COSP model corrects the conversion in real time using three inputs: channel geometry (width and side slope for rectangular, trapezoidal or compound sections), the wetted area corresponding to the live water level, and multiple velocity samples from multi-point measurement. Instead of a fixed velocity coefficient K (0.85-0.95), the model applies a conversion that adapts to actual conditions. On sites with large water-level swings or irregular sections, flow accuracy typically improves from ±5% to about ±2%.

• Multi-band operation (24 GHz / 10 GHz) supplies several velocity samples for fitting the velocity distribution
• Pairs with the visual fusion radar level gauge, or uses the integrated level channel, for real-time water level
• Section parameters and model configuration can be updated remotely via EC32/EC60 series RTUs

The more regular the section and the longer the straight reach, the more stable the COSP correction. For more information, please visit our product pages or contact our technical team.