ABSTRACT
Up= -(tc ·+l · + U·_l · ) 2 I 2 •) I 2 ,) (2) and ez and e11 are the unit co-ordinate vectors in X andy directions respectively. Each velocity vector consists of three separate straight line segments, i.e., AB, BC and BD as shown in Figure 2 where points A and B denote the vector tail and head respectively. If we assume that E is the mid-point of the line segment BP (or somewhere along the line segment AB) and that IECI = IEDI = oiABI, where o is a constant so that the vector head will be in proportion to the vector sizes, then the graphics screen co-ordinates for points A, B, C and D can be determined using the following formulae:-
Figure 3: Plotting of the Predicted Velocities in Poole Harbour
where Sv x and Svy are the velocity scaling factors in the X and Y directions respectively, and
if X..t = XB; if X..t = XBi
(7)
in which T.-tB = (YB-l~t)/(XB-X..t). Connecting AB, BC and BD with straight lines completes the vector drawing. As an application example, Figure 3 shows a predicted velocity field plot for a water quality study for Poole Harbour, located on the south coast of the U.J(.
