docs: VIV predeclare — U* = 5.0, verified f_N convention, c_crit and target OPEN

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/validation/leontini_viv_predeclare.md

@@ -11,14 +11,23 @@ record; nothing here re-scores it. No code until this page is agreed.
   doi:10.1016/j.jfluidstructs.2006.04.003. 2-D, one transverse DOF,
   Re = 200, m* = m/m_f = 10, zeta = 0.01; U* = U/(f_N D), f_N natural frequency
   in fluid with inviscid added mass (as read by Grok from the full text).
-- OPEN: c_crit convention (in-fluid vs vacuum); the chosen figure panel; the
-  digitized A*/D and f/f_N at the chosen U* with tool and digitization
-  uncertainty. No target number is used before these are recorded.
+- Verified (Grok, primary text, JFS §3.1): U* uses f_N in fluid "assuming an
+  inviscid added-mass term applies" (C_A = 1); the paper also plots f/f_N,vac.
+  Companion: ANZIAM J. 46(E) C365–C378 (2005), doi:10.21914/anziamj.v46i0.965.
+- c_crit: both papers write zeta = c/c_crit without defining c_crit. OPEN for
+  the owners: (a) structural 2 sqrt(k m) or (b) effective 2 sqrt(k (m + m_A)).
+  The difference in c is sqrt(11/10) ≈ 5 % at m* = 10; the choice is declared
+  before any run and the other is not substituted afterwards.
+- Target: digitized A*/D and f/f_N at U* = 5.0 from Fig. 1 (tool and
+  digitization uncertainty recorded). OPEN until that digitization exists; no
+  target number is used before it.
 
 ## Case (one locked point; a sweep is a separate decision)
 
-- One U* inside the primary lock-in band, chosen from the paper's own figure
-  before any run (OPEN, with its digitized A*, f/f_N).
+- U* = 5.0: the paper's own example of a periodic, constant-amplitude,
+  stable-phase response (Fig. 3); avoids the intermittent upper-type range
+  U* in (4.2, 4.7) (Fig. 2 at U* = 4.6, transition near 4.7). Chosen from the
+  paper's prose before any run.
 - D = 40 (matches the prescribed stage), MRT, dense double buffer, native
   channel: uniform inlet U_lat = .04, NEQ outlet, slip y walls; box 40 D × 20 D
   (blockage .05), cylinder 10 D from the inlet — a reproduction choice.