Hematocrit Centrifuge 2D: Stokes-Law Blood Separation

A microhematocrit centrifuge is one of the oldest and still most-used diagnostic tools in medicine: spin whole blood fast enough and long enough, and it separates into three visible layers purely by density — packed red cells at the bottom, a thin buffy coat of white cells and platelets above them, and straw-colored plasma on top. This 2D simulator drives that separation with the real underlying physics: a draggable top-down rotor view shows the sample tube swing out from vertical toward horizontal as RPM rises, while a live tube cross-section computes each cell type's settling velocity directly from Stokes' law — radius squared, density difference, and plasma viscosity — rather than a fixed visual speed ratio. Adjust rotor speed and radius to change the relative centrifugal force (RCF), dial in a patient's true hematocrit to simulate anemia or polycythemia, or tune plasma viscosity and red-cell radius to see exactly how each physical parameter changes the settling velocity and the time to a clean separation.