Update Tangent_ShearViscosity_StrainRate (#124)

ryanblack129 · web-flow · commit d02c6d5129c1 · 2026-03-06T10:22:02.000-07:00
diff --git a/FEBioFluid/FEBinghamFluid.cpp b/FEBioFluid/FEBinghamFluid.cpp
@@ -103,12 +103,12 @@ double FEBinghamFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)
 {
 	FEFluidMaterialPoint& vt = *mp.ExtractData<FEFluidMaterialPoint>();
 	mat3ds D = vt.RateOfDeformation();
-	double dmu = 0;
+	double dmu_dgdot = 0;
 	double gdot = sqrt(2 * (D.sqr()).tr());
 	if (gdot > 0) {
-		dmu = m_tauy / pow(gdot, 2) * ((1 + m_n * gdot) * exp(-m_n * gdot) - 1);
+		dmu_dgdot = m_tauy / pow(gdot, 2) * ((1 + m_n * gdot) * exp(-m_n * gdot) - 1);
 	}
-	return dmu;
+	return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------
diff --git a/FEBioFluid/FECarreauFluid.cpp b/FEBioFluid/FECarreauFluid.cpp
@@ -105,7 +105,9 @@ double FECarreauFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)
 
 	double dmu = 2 * (m_mu0 - m_mui) * (m_n - 1) * m_lam * m_lam * pow(1 + lamg2, (m_n - 3) * 0.5);
 
-	return dmu;
+   double dmu_dgdot = 0.5 * gdot * dmu;
+
+   return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------
diff --git a/FEBioFluid/FECarreauYasudaFluid.cpp b/FEBioFluid/FECarreauYasudaFluid.cpp
@@ -110,7 +110,9 @@ double FECarreauYasudaFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint&
 	double dmu = (m_a >= 2) ? 2 * (m_mu0 - m_mui) * (m_n - 1) * pow(m_lam, m_a) * pow(gdot, m_a - 2)
 		* pow(1 + lamga, (m_n - m_a - 1) / m_a) : 0;
 
-	return dmu;
+	double dmu_dgdot = 0.5 * gdot * dmu;
+
+   return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------
diff --git a/FEBioFluid/FECrossFluid.cpp b/FEBioFluid/FECrossFluid.cpp
@@ -106,7 +106,9 @@ double FECrossFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)
 
 	double dmu = -2 * (m_mu0 - m_mui) * m_m * pow(m_lam, m_m) * pow(gdot, m_m - 2) / pow(1 + pow(lamg, m_m), 2);
 
-	return dmu;
+	double dmu_dgdot = 0.5 * gdot * dmu;
+
+   return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------
diff --git a/FEBioFluid/FEPowellEyringFluid.cpp b/FEBioFluid/FEPowellEyringFluid.cpp
@@ -107,7 +107,9 @@ double FEPowellEyringFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& m
 	double dmu = (lamg < 1e-3) ? -2 * (m_mu0 - m_mui) * m_lam * m_lam / 3. :
 		(2 * (m_mu0 - m_mui) * (gdot / sqrt(1 + pow(lamg, 2)) - asinh(lamg) / m_lam)) / pow(gdot, 3);
 
-	return dmu;
+	double dmu_dgdot = 0.5 * gdot * dmu;
+
+   return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------
diff --git a/FEBioFluid/FEQuemadaFluid.cpp b/FEBioFluid/FEQuemadaFluid.cpp
@@ -107,7 +107,10 @@ double FEQuemadaFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)
 	double gdot = sqrt(2 * (D.sqr()).tr());
 	double grsqrt = sqrt(gdot / m_gc);
 	double dmu = (gdot > 0) ? 4 * m_mu0 * m_H / m_gc * (m_k0 - m_ki) * (1 + grsqrt) / grsqrt / pow(-2 * (1 + grsqrt) + m_H * (m_k0 + m_ki * grsqrt), 3) : 0.0;
-	return dmu;
+	
+   double dmu_dgdot = 0.5 * gdot * dmu;
+
+   return dmu_dgdot;
 }
 
 //-----------------------------------------------------------------------------

Original file line number	Diff line number	Diff line change
`@@ -103,12 +103,12 @@ double FEBinghamFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)`
`103`	`103`	`{`
`104`	`104`	`FEFluidMaterialPoint& vt = *mp.ExtractData<FEFluidMaterialPoint>();`
`105`	`105`	`mat3ds D = vt.RateOfDeformation();`
`106`		`- double dmu = 0;`
	`106`	`+ double dmu_dgdot = 0;`
`107`	`107`	`double gdot = sqrt(2 * (D.sqr()).tr());`
`108`	`108`	`if (gdot > 0) {`
`109`		`- dmu = m_tauy / pow(gdot, 2) * ((1 + m_n * gdot) * exp(-m_n * gdot) - 1);`
	`109`	`+ dmu_dgdot = m_tauy / pow(gdot, 2) * ((1 + m_n * gdot) * exp(-m_n * gdot) - 1);`
`110`	`110`	`}`
`111`		`- return dmu;`
	`111`	`+ return dmu_dgdot;`
`112`	`112`	`}`
`113`	`113`
`114`	`114`	`//-----------------------------------------------------------------------------`
Original file line number	Diff line number	Diff line change
`@@ -105,7 +105,9 @@ double FECarreauFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)`
`105`	`105`
`106`	`106`	`double dmu = 2 * (m_mu0 - m_mui) * (m_n - 1) * m_lam * m_lam * pow(1 + lamg2, (m_n - 3) * 0.5);`
`107`	`107`
`108`		`- return dmu;`
	`108`	`+ double dmu_dgdot = 0.5 * gdot * dmu;`
	`109`	`+`
	`110`	`+ return dmu_dgdot;`
`109`	`111`	`}`
`110`	`112`
`111`	`113`	`//-----------------------------------------------------------------------------`
Original file line number	Diff line number	Diff line change
`@@ -110,7 +110,9 @@ double FECarreauYasudaFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint&`
`110`	`110`	`double dmu = (m_a >= 2) ? 2 * (m_mu0 - m_mui) * (m_n - 1) * pow(m_lam, m_a) * pow(gdot, m_a - 2)`
`111`	`111`	`* pow(1 + lamga, (m_n - m_a - 1) / m_a) : 0;`
`112`	`112`
`113`		`- return dmu;`
	`113`	`+ double dmu_dgdot = 0.5 * gdot * dmu;`
	`114`	`+`
	`115`	`+ return dmu_dgdot;`
`114`	`116`	`}`
`115`	`117`
`116`	`118`	`//-----------------------------------------------------------------------------`
Original file line number	Diff line number	Diff line change
`@@ -106,7 +106,9 @@ double FECrossFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& mp)`
`106`	`106`
`107`	`107`	`double dmu = -2 * (m_mu0 - m_mui) * m_m * pow(m_lam, m_m) * pow(gdot, m_m - 2) / pow(1 + pow(lamg, m_m), 2);`
`108`	`108`
`109`		`- return dmu;`
	`109`	`+ double dmu_dgdot = 0.5 * gdot * dmu;`
	`110`	`+`
	`111`	`+ return dmu_dgdot;`
`110`	`112`	`}`
`111`	`113`
`112`	`114`	`//-----------------------------------------------------------------------------`
Original file line number	Diff line number	Diff line change
`@@ -107,7 +107,9 @@ double FEPowellEyringFluid::Tangent_ShearViscosity_StrainRate(FEMaterialPoint& m`
`107`	`107`	`double dmu = (lamg < 1e-3) ? -2 * (m_mu0 - m_mui) * m_lam * m_lam / 3. :`
`108`	`108`	`(2 * (m_mu0 - m_mui) * (gdot / sqrt(1 + pow(lamg, 2)) - asinh(lamg) / m_lam)) / pow(gdot, 3);`
`109`	`109`
`110`		`- return dmu;`
	`110`	`+ double dmu_dgdot = 0.5 * gdot * dmu;`
	`111`	`+`
	`112`	`+ return dmu_dgdot;`
`111`	`113`	`}`
`112`	`114`
`113`	`115`	`//-----------------------------------------------------------------------------`