Crucially, Flow-3D can model the "shrinkage flow." As the density of the metal changes with temperature, the software calculates the volume deficit. If the geometry of the part or the viscosity of the mushy zone prevents liquid from back-filling this deficit, the solver registers a drop in hydrostatic pressure. In advanced applications, users can couple this pressure calculation with a failure criterion. If the pressure drops below a specific threshold (the cavitation pressure or the material’s fracture stress), the simulation can visualize the nucleation of a void, effectively predicting the crack location.
: The conditions during hydro-cracking are extreme, requiring robust models that can handle high pressures and possible thermal effects.
In metal casting, (or hot tearing) occurs during solidification when thermal stresses exceed the material's strength while it is still in a semi-solid state. Understanding Hot Cracking in FLOW-3D
If this thermal cycle happens concurrently with high hydraulic pressures ("hydro"), the structural risk multiplies: flow 3d hydro crack hot
To accurately run a simulation, the software leverages three core modules working in unison.
Hydraulic fracturing, commonly known as fracking, is a process used to extract oil and natural gas from shale rock formations. It involves injecting high-pressure water, sand, and chemicals into the rock to create fractures, through which the oil or gas can then flow out. However, this process can have significant environmental and operational risks, including the potential for induced seismicity, groundwater contamination, and surface water pollution.
Thermal cracking—often referred to as "hot cracking" or thermal shock degradation—occurs when localized temperature gradients produce internal stresses that exceed the tensile capacity of a material. In civil hydro infrastructure, such as dam spillways, industrial outfall channels, energy dissipation pools, and industrial cooling loops, this phenomenon is usually triggered by two distinct mechanisms: Crucially, Flow-3D can model the "shrinkage flow
Advanced CFD (Computational Fluid Dynamics) simulations use several modules to track the risk of cracking:
Flow-3D Hydro’s algorithm allows users to define a "porous zone" that transitions into a "void zone" as the crack opens, creating a dynamic feedback loop.
Whenever possible, validate your model against experimental measurements or field observations. The studies on the Aghchai and Gelevard‑Neka spillways both emphasized the importance of aligning simulation results with empirical data to confirm model reliability. If the pressure drops below a specific threshold
+-----------------------------------------------------------+ | FLOW-3D Multi-Physics Solver | +-----------------------------------------------------------+ | +----------------------+----------------------+ | | v v [ Fluid & Thermal Dynamics ] [ Structural Mechanics ] - Free-Surface tracking (TruVOF) - Thermal contraction strain - Phase change (Solid/Liquid) - Pore pressure buildup - Intense Marangoni convection - Tensile stress evaluation | | +----------------------+----------------------+ | v [ Hot Cracking Vulnerability Map ] Free-Surface Tracking via TruVOF
: Look for regions with high shear stress at the solid-liquid interface during the critical temperature range (just before full solidification). 2. Hydrofracturing in Hot Rock (EGS)
The simulation predicts a "runaway crack" (full-depth fracture) within 10 seconds—a failure mode impossible to see with rigid-body assumptions.
The solver includes dedicated liquid-solid and liquid-vapor phase change models paired with thermal stress evolution modules. This allows engineers to track the exact moments when thermal shrinkage transitions into structural cracking. Step-by-Step Simulation Workflow