[will.jones1995]

Hello everyone,

I'm hoping someone will be able to help me with an error on my UFD. I should start by saying that I have no knowledge of C, so a coding error was going to happen.


The Problem

I have the geometry shown in the image below, I want an fully developed velocity profile at the inlet with an x component.



The velocity components for the flow profile are shown below:

u/ui = 2(1-r^2), v/ui = 0 and w/ui = 0


My Code

As I said previously, I've no knowledge of C and there's an error in here somewhere. I've tried a couple of different things (including Googling), but I just can't seem to get it to work, so any help would be massively appreciated.

#include "udf.r"

DEFINE_PROFILE(inlet_x_velocity, thread, position)
{
	real x[ND_ND];    /* this will hold the position vector */
	real y;
	face_t f;

	r = 0.0127; /* radius in m */

	begin_f_loop(f,t)
	{
	F_CENTROID(x,f,t);
	y = x[1];
	F_PROFILE(f,t,i) = 2 * (1 - (r * r))
	}
	end_f_loop(f,t)
}

If anyone knows how to fix this to get it to work, I will be very grateful.

Thanking you all in advance,

Will

[pakk]

If you try to compile this code, it does not work. You get errors. What you should do: read those errors!


The first error that I get:

..\..\src\temp.c(1): fatal error C1083: Cannot open include file: 'udf.r': No such file or directory

So, the compiler complains that it can not find the file "udf.r". Why does it look for that file? Because you told it to. You made a typo: it should be "udf.h", as it is in all examples in the Fluent manual.


OK, so I fixed that, and compiled again. Again errors:

..\..\src\temp.c(9): error C2065: 'r': undeclared identifier ..\..\src\temp.c(11): error C2065: 't': undeclared identifier
..\..\src\temp.c(11): error C2223: left of '->nelements_in_layer' must point to struct/union
..\..\src\temp.c(13): error C2065: 't': undeclared identifier
..\..\src\temp.c(13): error C2223: left of '->storage' must point to struct/union
..\..\src\temp.c(15): error C2065: 't': undeclared identifier
..\..\src\temp.c(15): error C2223: left of '->storage' must point to struct/union
..\..\src\temp.c(15): error C2065: 'i': undeclared identifier
..\..\src\temp.c(15): error C2065: 'r': undeclared identifier
..\..\src\temp.c(16): error C2143: syntax error: missing ';' before '}'

Always start on the top. The first error is that 'r' is undeclared. So the solution: declare it! Tell the compiler what 'r' is. You want it to be a variable that is a floating number. Similarly, you use 't' and 'i', but you never told the compiler what they are. I don't know where you started from, but actually 't' should be the same as 'thread' in the declaration, and 'i' should be the same as 'position' in the declaration.


After fixing that, I compile again, and see one error remaining:

..\..\src\temp.c(16): error C2143: syntax error: missing ';' before '}'

Aha, you forgot to put a semicolon after your statement.


I added the semicolon, and the compilation went perfect.


So to conclude: compile, and look at the errors. You might not understand the error, but if you don't try you'll never know.

[will.jones1995]

Thanks pakk, that was really helpful.