Figure 4

Phase plane solutions. The phase plane diagrams are given for (a) fine grind parameters \(\epsilon= 0.028\), \(b_{1} = 5.239\), \(b_{2} =2.897\) and \(\gamma_{1}=0.70\) (JK drip filter grind) and (b) coarse grind parameters \(\epsilon= 0.071\), \(b_{1} = 1.99\), \(b_{2} =1.35\) and \(\gamma_{1}=0.5\) (Cimbali #20 grind). Solution trajectories and direction fields are plotted in both cases. The magnitude of the direction field is represented by the size of the blue direction vectors.