Jim Kelley wrote:
I don't think anyone believes that standing waves alternate in
direction.

The currents are referenced to the source. When the forward
current and reflected current are in phase at zero degrees,
they are at a maximum and flowing toward the load so their sum,
the net current, is flowing toward the load. 1/2 cycle later,
the forward current and reflected current are in phase at
180 degrees so their sum, the net current, is flowing toward
the source.

You need to think more carefully about what a standing wave is.

You need to understand that AC current flows one direction for 1/2
cycle and the opposite direction for the other 1/2 cycle. Current
cannot stand still. It must flow. And if it's AC current, it
always changes direction during the cycle. Standing current waves
are AC and neither DC nor AC current can stand still. If you install
a one ohm resistor at a current maximum point, the voltage in phase
with the current will be changing phase by 180 degrees every 1/2
cycle. The sign of the cosine of the current phase indicates direction.

It's not a matter of current flow into or current flow out of; for a
standing wave plot it's a matter of the magnitude of current flowing
*AT* the specific positions.

Current cannot flow "at" a specific position, Jim. Current has to flow
through a specific position in one of two directions. For 1/2 cycle, it
flows in one direction and for the other 1/2 cycle it flows in the opposite
direction. Like I said, the seduction by your math models is worse than I
thought.

At everywhere except the current nulls, the standing wave current changes
directions every 1/2 cycle. May I suggest you review phasor addition and
the meaning of the sign of the cosine phase when dealing with current.
--
73, Cecil, W5DXP