Model Selection for Biological Blockage at Cooling Water Intakes: A Structured Critical Review of CFD, FSI, CFD–DEM, and Surrogate Models

The biological blockage of cooling water intakes links regional transport, local hydraulics, barrier deformation, organism contact, and operational recovery. This structured critical review connects these physical subproblems to computational fluid dynamics (CFD), fluid–structure interaction (FSI), CFD–discrete element methods (CFD–DEM), resolved-interface methods, and surrogates. We distinguish contextual relevance from validation strength and compare reported numerical checks, experimental comparisons, and calibration dependence. Calibrated reduced-screen CFD provides a candidate starting point for flow and head loss within its tested regime. FSI becomes necessary when deformation or dynamic feedback changes a decision-relevant response; agreement in mean load alone cannot establish peak load credibility. CFD-DEM is restricted to populations whose quasi-rigid-body and unresolved flow assumptions are defensible. Soft-body passage and entanglement require additional constitutive and interaction evidence. Surrogates require separate assessment of approximation errors, source-model validity, and domain shift. Integrating established verification and validation principles, we present a quantity-first selection map and an explicitly hypothetical numerical example linking model enrichment, uncertainty, and an acceptance margin. The principal evidence gap remains independent intake-specific validation across hydraulic, structural, and object-level responses.