Add adaptive CFL and CFL checks.

Author: sbryngelson

config.m

@@ -89,6 +89,20 @@
       error('Unknown geometry type: %s. Supported types: cylinder, ellipse, rectangle, airfoil, multi', geometry_type);
   end
 
+  % Time-based simulation control (alternative to num_time_steps)
+  config.simulation.use_end_time = false;     % If true, use end_time instead of num_time_steps
+  config.simulation.end_time = 20;          % Simulation end time (when use_end_time = true)
+  config.simulation.end_time_ci = 0.2;        % Reduced end time for CI/testing
+
+  % Adaptive time step control
+  config.adaptive_dt.enable = false;                    % Enable adaptive time step reduction
+  config.adaptive_dt.cfl_threshold = 0.5;              % Convective CFL threshold for time step reduction (lowered for stability)
+  config.adaptive_dt.cfl_viscous_threshold = 0.5;     % Viscous CFL threshold (nu*dt/h^2 < threshold)
+  config.adaptive_dt.reduction_factor = 0.2;           % Factor to reduce time step by (dt_new = dt * factor)
+  config.adaptive_dt.min_factor = 0.001;               % Minimum time step as fraction of original (dt_min = dt_0 * min_factor)
+  config.adaptive_dt.max_reductions = 10;              % Maximum number of consecutive reductions allowed
+  config.adaptive_dt.nan_check_enable = true;          % Enable NaN checking after time step reduction (stops simulation if found)
+
   %% RBF-FD Algorithm Parameters
   % Main stencil sizes
   config.rbf.stencil_size_main = 35;
@@ -138,11 +152,16 @@
 
   %% Logging and Debug Parameters
   % Master debug switch - set to true to enable all debug features
-  debug_master = false;                         % Master switch for all debug features
+  debug_master = false;                                % Master switch for all debug features
+
+  % Local CFL diagnostics
+  config.logging.cfl_check_frequency = 1;             % Run local CFL check every N steps
+  config.logging.cfl_local_enable = true;              % Enable per-node CFL checks
+  config.logging.cfl_percentiles = [90 99];         % Percentiles to report
 
   % Individual debug settings (controlled by master switch unless overridden)
   config.logging.enable = debug_master;                % Enable debug logging
-  config.logging.step_frequency = 3;                   % Print diagnostics every N steps
+  config.logging.step_frequency = 1;                   % Print diagnostics every N steps
   config.logging.trace_substeps = debug_master;        % Print substep diagnostics inside fractional step
   config.logging.snapshot_on_nan = debug_master;       % Save snapshot if NaN detected
   config.logging.snapshot_dir = 'debug';               % Directory to save debug snapshots
@@ -164,11 +183,16 @@
   % Stability thresholds
   config.logging.cfl_warning_threshold = 0.8;          % Warn if CFL > this value
   config.logging.cfl_critical_threshold = 1.5;         % Critical CFL threshold
-  config.logging.velocity_explosion_threshold = 100;  % Velocity magnitude explosion threshold
-  config.logging.pressure_explosion_threshold = 1000; % Pressure explosion threshold
+  config.logging.cfl_stop_threshold = 0.9;             % Stop simulation if CFL > this value (always active)
+  config.logging.velocity_explosion_threshold = 100;   % Velocity magnitude explosion threshold
+  config.logging.pressure_explosion_threshold = 1000;  % Pressure explosion threshold
   config.logging.divergence_warning_threshold = 10;    % Mass conservation warning
   config.logging.divergence_critical_threshold = 100;  % Mass conservation critical
   config.logging.condition_number_threshold = 1e12;    % Matrix conditioning threshold
+  config.logging.immediate_nan_check = true;           % Check for NaNs immediately after each time step
+  config.logging.comprehensive_instability_check = true;  % Check for all types of instability (not just NaNs)
+  config.logging.periodic_health_check = false;        % Periodic health checks during simulation
+  config.logging.health_check_frequency = 10;         % Health check every N steps
 
   % Environment override for enabling logging
   dbg_env = getenv('DEBUG');