(SSL Module Only)

One of the distinct aspects of settling slurry behavior is the minimum point of the system curve. This means that for a given jm (or, in general, head difference) there are two potential flowrates, as is shown in Figure 1 below. This has the potential for unstable numerical results.

It is recommended that the system operate with a velocity ratio (V_m/V_sm) somewhat greater than 1.0 in all pipes so that solids will not settle out of the carrier fluid and form a stationary bed (which is not modeled using the SSL module) or plugging the pipe.

Often it is common practice to operate at or above the minimum im/jm point to achieve a desirable velocity ratio, and to avoid higher head losses that can occur to the left of the im/jm minimum. For example, in the below figure the minimum im occurs at about 5.25 m/s, so a mean velocity of 5.25 m/s or greater would be favorable. Model convergence may be difficult the closer the velocity ratio is to 1.0. Note that head loss curves like the one shown below will vary at different values of pipe diameter and solids concentration.