blink e1 e2 [-b break] [-l rest] [-s stiff]
blink creates struts between entity e1 and entity e2. A strut consists of a sequence of three links at every immersed point on both entities, except possibly at the endpoints. The links themselve form an overlapping network.
blink requires two 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.
blink interpretes 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
To use blink, the two entities that are linked must have an identical number of immersed boundary points. The user can ensure this by using the -n command when specifying the entities.
The strut links are formed by the following method. Let xj be the jth point on entity e1 and let Xj be the jth point on entity e2. Then a link is formed from xj to Xj, from xj to Xj-1, and from xj to Xj+1. This is repeated at every point on entity e1. If the entities are periodic, then the logical links between the first and last points are included. If the entity is not periodic, the first and last points on both entites have only two links. Draw a picture, you will easily see why.
To make a logical linking structure, the first point on entity e1 should be closer to the first point on entity e2 than to any other point on entity e2. This is not required for the blink command.
spring, link, olink, slink
circle 0.25 1.25 0.05 -N 1 -n 100 circle 0.25 1.25 0.07 -N 2 -n 100 blink 1 2
This code establishes a 300 link strut network between the two concentric circles. This forms a stiff ring or annulus.