From d3b96730bd01263098bbb96c15148878e5633a04 Mon Sep 17 00:00:00 2001
From: Prefetch
Date: Sat, 8 May 2021 16:08:41 +0200
Subject: Expand knowledge base, change text alignment

---
 content/know/concept/reynolds-number/index.pdc | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'content/know/concept/reynolds-number')

diff --git a/content/know/concept/reynolds-number/index.pdc b/content/know/concept/reynolds-number/index.pdc
index bd18f2f..ff5e793 100644
--- a/content/know/concept/reynolds-number/index.pdc
+++ b/content/know/concept/reynolds-number/index.pdc
@@ -25,6 +25,12 @@ $$\begin{aligned}
     = - \frac{\nabla p}{\rho} + \nu \nabla^2 \va{v}
 \end{aligned}$$
 
+In this case, the gravity term $\va{g}$
+has been absorbed into the pressure term:
+$p \to p\!+\!\rho \Phi$,
+where $\Phi$ is the gravitational scalar potential,
+i.e. $\va{g} = - \nabla \Phi$.
+
 Let us introduce the dimensionless variables $\va{v}'$, $\va{r}'$, $t'$ and $p'$,
 where $U$ and $L$ are respectively a characteristic velocity and length
 of the system at hand:
@@ -108,7 +114,7 @@ such that redimensionalizing yields:
 
 $$\begin{aligned}
     \pdv{\va{v}}{t} + (\va{v} \cdot \nabla) \va{v}
-    = - \nabla p
+    = - \frac{\nabla p}{\rho}
 \end{aligned}$$
 
 Which is simply the main [Euler equation](/know/concept/euler-equations/)
@@ -133,7 +139,8 @@ $$\begin{aligned}
 
 This equation is called the **unsteady Stokes equation**.
 Usually, however, such flows are assumed to be steady
-(i.e. time-invariant), leading to the **steady Stokes equation**:
+(i.e. time-invariant), leading to the **steady Stokes equation**,
+with $\eta = \rho \nu$:
 
 $$\begin{aligned}
     \boxed{
-- 
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