Fibrin clot in the presence of flow. Computer simulations were performed as described under the Methods section. Size of simulation area 1000 μm × 6000 μm; activator size 1000 μm. The time is 0 min (a), 15 min (b) and 25 min (c) since the beginning of coagulation, wall shear rate is 17 s-1. Arrow shows the direction of flow. Blue-red gradient shows the value of horizontal component of flow velocity: the more reddish is the colour, the greater is this component. Top and bottom boundaries are impermeable to flow. Green line at the bottom is activator (site, covered with TF). Dark gray shows solid clot (fibrin exceeds 3,800 nM). Dark blue shows the rest of the clot, consisting of low concentration fibrin. The detailed kinetics of thrombus formation can be found in Additional files 1 and 2.