Weissenberg-Rabinowitsch Shear Rate Calculator

Capillary & Slit Die Rheometry: Correct apparent Newtonian shear rate ($\dot{\gamma}_{app}$) to true non-Newtonian wall shear rate ($\dot{\gamma}_w$).

Capillary Die Geometry

Capillary Bore Radius $R$ (mm):

Capillary Length $L$ (mm):

Experimental Flow Data

Flow Rate $Q$ (cm³/min):

Pressure Drop $\Delta P$ (bar):

Log Slope / Power-Law Index $n'$:

True Wall Rheology Output

True Wall Shear Rate ($\dot{\gamma}_w$)

-- s⁻¹

Apparent γ_app: -- s⁻¹

True Wall Shear Stress ($\tau_w$)

-- kPa

True Viscosity: -- Pa·s

Rabinowitsch Factor ($F_{WR}$)

Correction: +-- %

Apparent Viscosity ($\eta_{app}$)

-- Pa·s

True/Apparent: --

Weissenberg-Rabinowitsch Formulation:

• Apparent rate: $\dot{\gamma}_{app} = \frac{4 Q}{\pi R^3}$. True wall rate: $\dot{\gamma}_w = \dot{\gamma}_{app} \left( \frac{3n' + 1}{4n'} \right)$.

• Because pseudoplastic velocity profiles are flatter than parabolic Poiseuille flow, wall shear rate is $20$–$60\%$ higher.

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Weissenberg-Rabinowitsch Shear Rate Calculator

Capillary Die Geometry

Experimental Flow Data

True Wall Rheology Output

Frequently Asked Questions