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[chiara modenese <c.modenese@xxxxxxxxx>]

> delta_u = delta_u(real_vel) + gradVel*pos*dt; (1)
>>>
>>> delta_v = vel + gradVel*pos; (2)
>>>
>>
>>>
>> Heh, no! If you derive (1) vs. time, it will not give (2).
>> First, divide (1) by dt to get instantaneous quantities :
>>
>> du/dt = vel = du_real/dt + gradVel*pos = v_real + gradvel*pos
>>
>
Why do you say it is "instantaneous"? As I said, dt and delta_u are both
incremental quantities, hence this cannot be the instantaneous velocity
(which instead would be given by the derivative), it is the average of
velocity in delta_t. Am I wrong?