**NAME**

link

**SYNOPSIS**

link e1 e2 nl [-b break] [-l rest] [-s stiff]

**DESCRIPTION**

linkcreatesnlelastic links between entitye1 and entitye2. The links are created so that there is at most one link connecting each point on entitye1 to a point on entitye2 and vice-versa. The links are created between the closest pair of non-linked immersed boundary points. Note that immersed boundary points may have more than one link only if the links are to distinct entities.

linkrequires three arguments. These are:To link two entities, they must each be named. Therefore, in the definition of those entities, the -N or -A flags must be used.

- e1 - the name of one of the linked entities.
- e2 - the name of the other linked entity.
- nl - the number of links between the two entities.

linkinterpretes the following options.

- -b break = link breaking length(as a fraction of the initial length)
- -l rest = link resting length (as a fraction of the initial length)
- -s stiff = stiffness of the elastic springs

**SEE ALSO**

spring,blink,olink,slink

**EXAMPLE**

circle 0.25 1.25 0.05 -N 1 circle 0.15 1.25 0.05 -N 2 link 1 2 4 -b 4.0

This code establishes four links between the two circles that break when the length of the links stretchs past 4 times the initial length of the link. The resting length of these links is the initial length of the link.The four links are created between 4 distinct pairs of immersed boundary points, and the pairs consist of one immersed boundary point on each entity. The pairs are selected so that the links are the shortest possible.

**NOTE**

The algorithm to find the link locations is anO(nl)^{2}method, but it is used only at startup. Therefore, asnlgrows, the startup time increases, so be patient. To preview the IBIS file, usenlsmall, then increasenlas needed for the simulation.