How to compute the total viscous energy loss from 3D velocity flow field ?

msmmelbaz · August 20, 2014, 13:35

I am trying to compute the total energy viscous energy loss of the left ventricle . The velocity data is 3D velocity field acquired using 4D Flow MRI. I am wondering, when computing the cumulative energy loss should I sum the absolute (i.e. unsigned or non negative) values of the individual measurements or the signed ones?

To compute the energy loss of every point I use the following function:

E_loss=(S-(div(v)/3)*delta), where S is the strain rate tensor and delta is the Kronecker delta

Thanks in advance

msmmelbaz · August 21, 2014, 04:54

I would like to clarify my question more.
I do understand the point that divergence has to be signed. My question is about getting the total E-loss over all points in the domain of interest (In my case, Left ventricle ) i.e. when summing up the E-loss of all (x,y,z) mesh points should I sum the signed or unsigned E-loss? On other words, does negative E-loss represent something?

August 20, 2014, 13:35	How to compute the total viscous energy loss from 3D velocity flow field ?	#1
msmmelbaz New Member Mohammed ElBaz Join Date: Aug 2014 Posts: 2 Rep Power: 0	I am trying to compute the total energy viscous energy loss of the left ventricle . The velocity data is 3D velocity field acquired using 4D Flow MRI. I am wondering, when computing the cumulative energy loss should I sum the absolute (i.e. unsigned or non negative) values of the individual measurements or the signed ones? To compute the energy loss of every point I use the following function: E_loss=(S-(div(v)/3)*delta), where S is the strain rate tensor and delta is the Kronecker delta Thanks in advance

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August 21, 2014, 04:54		#2
msmmelbaz New Member Mohammed ElBaz Join Date: Aug 2014 Posts: 2 Rep Power: 0	I would like to clarify my question more. I do understand the point that divergence has to be signed. My question is about getting the total E-loss over all points in the domain of interest (In my case, Left ventricle ) i.e. when summing up the E-loss of all (x,y,z) mesh points should I sum the signed or unsigned E-loss? On other words, does negative E-loss represent something?