What is the verb that describe sand dropping across a face or a wall?

Question

What is the verb that describe sand dropping across a face or a wall?

I first looked for dripping but it seemed that dripped is only used for liquids.

Answer 1

Sand can flow through an hourglass—as well as across a face or down a wall.

[Merriam-Webster]
1 a (1) : to issue or move in a stream
// rivers flow into the sea
1 a (2) : CIRCULATE
1 b : to move with a continual change of place among the constituent particles
// molasses flows slowly
// water flowing over the dam

Although sand, unlike the example sentences, is made up of dry particles, flow is still appropriate.

Note that sand can also pour across a face or down a wall, but it's likely you want the movement to be slower than that verb expresses.