Every second, "Use" consumes a fixed throughput of material. In the linear model that entire throughput exits to a landfill and must be replaced next cycle by freshly extracted virgin material. In the circular model, a slice of that same outflow — the circularity rate — is diverted into recycling, reuse and repair and routed back into Production, directly displacing the equivalent amount of virgin extraction.
virgin = throughput × (1 − circularity)
recycled = throughput × circularity
landfill += throughput × (1 − circularity)
- Circularity rate — the fraction of used material recovered and looped back into production instead of discarded. 0% is a pure linear economy; 100% is a fully closed loop with (in this simplified model) no virgin extraction at all.
- Flow speed — how fast particles travel the network; scales simulated time, not the underlying rates.
- Compare — runs a 0%-circularity reference alongside your chosen rate so the gap in virgin draw and landfill accumulation is visible directly.
Real-world relevance: this is the accounting logic behind circular-economy metrics like material circularity indicators (MCI) and extended producer responsibility (EPR) targets — small increases in recovery rate compound into large reductions in cumulative virgin resource extraction and landfill volume over many cycles.