<p>A numerical investigation is conducted on mixed convection of viscoplastic nanofluids, modeled as a Bingham plastic, within a ventilated enclosure incorporating relative slip velocity between the base fluid and nanoparticles. The enclosure features heated walls, with cold fluid entering through an inlet and exiting through an outlet on opposite vertical walls. The governing equations are solved using a control volume approach based on the two-phase nanofluid model to assess thermal performance and the influence of yield stress on flow behavior. Heat transfer characteristics are analyzed through the average Nusselt number, entropy generation, cup mixing temperature, and pressure drop. Slip effects induced by Brownian diffusion and thermophoresis enhance heat transfer compared to the homogeneous model. The impacts of Reynolds number, Richardson number, nanoparticles volume fraction, particle diameter, and Joule heating are examined. Results indicate that nanoparticles addition improves heat transfer more significantly than the accompanying rise in entropy generation and pressure drop, while the Bingham yield stress diminishes heat transfer but enhances thermal mixing. These findings provide valuable insights for optimizing the design and performance of viscoplastic nanofluids-based thermal systems.</p>