* the diameter of the cylinder is fixed at one and that the dimensions of the
* channel must be an integer multiple of this diameter. Consequently, the
* length before the cylinder
- * (length_pre, $L_{pre}$), the length after the cylinder (length_post, $L_{post}$) and the half height
- * of the channel (half_height, $H$) must be integer values. The geometry consists
- * of a channel of size $[-L_{pre}, -H] \times [L_{post}, H] \times [0, W] $
- * (where the $z$ dimension is omitted in 2d) with a cylinder, parallel to the
- * $z$ axis with diameter $1$, centered at $(0, 0, 0)$. The channel has three
- * distinct regions:
- * <ol>
+ * (length_pre, $L_{pre}$), the length after the cylinder (length_post,
+ * $L_{post}$) and the half height of the channel (half_height, $H$) must be
+ * integer values. The geometry consists of a channel of size $[-L_{pre}, -H]
+ * \times [L_{post}, H] \times [0, W] $ (where the $z$ dimension is omitted in
+ * 2d) with a cylinder, parallel to the $z$ axis with diameter $1$, centered
+ * at $(0, 0, 0)$. The channel has three distinct regions: <ol>
* <li>If @p n_shells is greater than zero, then there are that many shells
* centered around the cylinder,</li>
* <li>a blending region between the shells and the rest of the