##  [Spurious Currents](/spurious-currents-0) 

 Definition

Small, nonphysical velocity circulations that appear near interfaces in multiphase or interfacial flow simulations due to discretization imbalance, inconsistent surface tension treatment, or force discretization errors.

 

 

 

 

 

 





## Principle

Principle

Arise when discrete approximations of interfacial forces (for example capillary pressure or surface tension gradients) do not satisfy the same discrete balance as the momentum discretization, producing net tangential imbalances that drive parasitic vortices.

 

 

 

 

 





## Demonstration

Demonstration

In a volume-of-fluid simulation of a static droplet, an imprecise curvature calculation and inconsistent pressure-gradient discretization produce steady circular flows around the interface even though the analytical solution is quiescent.

 

 

 

 

## Misapplication

Misapplication

Interpreting spurious currents as genuine micro-scale circulation and using them to infer transport or mixing rates will produce erroneous physical conclusions and may hide modeling errors.

 

 

 

 

 





## Consequence

Consequence

Spurious currents lead to spurious mixing, artificial interface deformation, inaccurate mass/force balance near the interface, and can seed numerical instabilities or false coalescence/breakup events.

 

 

 

 

## Reversal

Reversal

A genuine interfacial flow is driven by actual thermodynamic or applied forces and scales predictably with physical parameters (surface tension, viscosity, body forces); it diminishes under consistent discretization and grid refinement, unlike spurious currents that reflect numerical imbalance.

 

 

 

 

 





## Boundary

Boundary

Relevant to multiphase, free-surface, and interfacial CFD methods where curvature, surface tension, or capillary terms are discretized; excludes real Marangoni flows, buoyancy-driven circulations, or physically imposed shear at boundaries.

 

 

 

 

 





## Semantic Tension

Semantic Tension

Closely related to 'parasitic currents' in literature; may be conflated with physically small but real flows (e.g., Marangoni convection) — the distinguishing feature is failure to vanish with improved discretization or corrected force balance.

 

 

 

 

 





## Synthesis

Synthesis

Spurious currents are numerically induced, nonphysical circulations at interfaces caused by inconsistent discretization of interfacial forces; identifying them requires convergence testing and ensuring discrete force-momentum consistency to remove artefactual flows.